In Ukraine, a crowd is enjoying a concert in an opera house when suddenly a group of masked men appear on the stage and start breaking the instruments while shooting people. Soon the Ukrainian special forces arrive at the same time as a bunch of CIA agents, including John. His group rushes inside with a clear mission: to rescue an American VIP and a special package.
Using fake uniforms, John’s team blends in with the special forces as they connect gas tanks to the vents to put everyone in the main stage to sleep. Then the team starts searching the VIP booths and John finds his objective, so he quickly brings down a couple of guards before telling the guy the password to confirm they’re allies. There are shooters coming down the corridor, so John grabs the man and they jump through the window using a rope.
The VIP then sits among the sleeping people to pretend he’s a random dude while John rejoins the team, only to notice a Ukrainian agent planting a bomb. John tells one of his men to protect the VIP while he grabs the bomb and runs to the coat station, where his contact has hidden the special package. Once he finds the metallic box, he runs to the maintenance room to reunite with his team and the VIP man, who tells them about a secret tunnel.
One of the agents changes clothes with him as part of their cover. While most of the team escort the VIP out through that tunnel, John and and the disguised teammate run back to the main room to pick the rest of the bombs. Suddenly a Ukrainian soldier points a gun at him and to John’s shock, the hole in the ground disappears and the bullet that caused it flies back, killing the soldier and entering the gun of a new man.
This guy quickly leaves and John notices a red string on his backpack. Next John puts all the bombs in a bag and throws them in the upper seats before he and his teammate run to the entrance, leaving the opera house right before the bombs explode. The duo gets in the back of a van and John's teammate immediately gets shot in the leg because the Ukrainians can tell he isn’t the right guy.
Moments later, John and his friend get tortured on a train yard for information. The Ukrainian takes the poison capsule that John is hiding in his clothes, but his friend still has one left. John falls to grab it with his mouth, quickly biting it and passing out.
Sometime later John wakes up on a medical bed inside a ship sailing. A high-ranking CIA agent explains that the capsule never had cyanide, only a sedative. It was just a way to test John’s loyalty to his country.
Now John has been chosen for a secret mission, yet the only information they give him is the code-word “Tenet”. When a mechanics’ ferry passes by, John pretends to be one of them and sneaks into their boat so he can return to land. After stealing a car, he goes to a lab in the city and meets with Laura, who recognizes the code-word.
Laura explains they’re trying to prevent World War III and that it could be worse than nuclear holocaust. Then Laura gives John an empty gun and when he shoots it, a bullet goes back into the weapon. Laura also makes a bullet jump into her hand and explains she is studying inverted objects.
These things have their entropy reversed in the future and travel backwards through time. John makes a bullet go to his hand too and Laura records it to show him the video, pointing out that from the bullet’s point of view he dropped it. John practices with the inverted gun while Laura tells him that all the items she studies were sent from the future.
They’ve found all kinds of parts from complex machines that indicate a catastrophic war will happen. John wants to know who is dealing the inverted guns and travels to Mumbai, where he meets with British operative Neil. Together they make a plan to infiltrate the home of a dangerous arm dealer.
In the evening, the duo gets on the roof of a neighboring building and use bungee cords to make a big jump, landing on the walls of the dealer’s home. They run up and sneak in through the balcony, where they quickly take out a bunch of guards before jumping on the dealer himself. John holds him at gunpoint as he asks about the inverted ammo, but it’s the man’s wife Priya who knows about Tenet.
She informs him that the dealer behind the inverted ammo is Russian oligarch Andrei, who knows how to communicate with the future. At that moment the police arrive, so Neil and John jump out of the building using the same cords. In London, John shares lunch with an agent from the British Intelligence.
The man explains that the best way to get close to Andrei would be through his wife Kat and her art gallery. Kat authenticated a forged Goya made by her friend Thomas and Andrei bought it, but when he found out the truth he started blackmailing Kat into becoming his partner. The agent gives John a new fake Goya so he can get a meeting.
Later John meets Kat and shows her the painting, saying he got it from Thomas. They end up having dinner together and Kat explains she hadn’t known the painting was a fake when she authenticated it. Andrei abuses her and Kat would love to escape, but they have a son and she can’t leave him behind.
Kat also reveals that Andrei brutalized Thomas, so she knows John is lying. John promises to retrieve the drawing Andrei is using to blackmail her if she gets him a meeting with her husband. Suddenly Andrei’s thugs arrive and take Kat away.
John tries to leave through the kitchen and finds more thugs, but he has no trouble beating them all up in minutes using random kitchen objects. The next day, John shows up at Kat’s son's school. Kat informs John that the drawing is being held in a freeport in Oslo, where Andrei's company does business without detection from the law.
Soon Neil shows up at the freeport while pretending to be an interested businessman and during the tour, he learns that in the case of fire, the interior doors of the vault room revert to their factory settings, making them weak to lock-picking. However the oxygen in that room will be sucked out because the company uses gas instead of sprinklers. John and Neil agree the best plan is to crash a plane into the freeport to trigger the lockdown.
They hire pilot Mahir, who brings his own team along. The duo goes to the freeport as businessmen and pretend they want to leave something in the vault, so an employee takes them there. Meanwhile Mahir’s team puts a bunch of workers to sleep to take over a plane.
As Mahir gets the plane moving, his men drop hundreds of gold bricks to distract any watchers and trick the incoming police. Once the plane has gained speed, the team sneaks out and lets it crash right into the building, causing a huge explosion. In the vault, the gas is being released and the employee immediately runs away.
Neil and John hold their breath while taking their hidden tools from their briefcase and picking the lock to open the door. They move around the vault picking different locks while trying to stay ahead of the gas. Eventually they enter a special corridor that takes them to Andrei’s private vault, where they cross a blue and a red door.
The duo finds themselves on different sides of the same room separated by a glass wall with bullet holes in it. On the floor, John notices a bunch of guns and realizes this hasn’t happened yet. Suddenly a thick revolving door spins on both sides and men in SWAT uniforms come out.
Neil is simply pushed as the guy runs off, so he follows him. Neil manages to jump on the man and remove his helmet, only to be shocked by what he sees. At the same time the other soldier attacks John and they get in a fight during which the attacker keeps calling the inverted guns to his hand to get back the bullets from the glass.
This man moves in a rather strange way and John realizes he’s inverted too. After lots of struggle, John manages to overpower him and gets the gun ready to shoot, but Neil arrives to stop him. John tries to ask for information, however the door opens and the inverted man slides backwards.
Outside a broken plane engine causes a second explosion. At that moment the paramedics arrive, so Neil and John pretend to be unconscious. The next day, John meets with Priya again.
She explains the revolting door must’ve been an inversion machine known as “turnstile”. The technology hasn’t been invented yet, someone sent it to Andrei from the future. The terrorists at the opera house were sent by Andrei, who wanted the plutonium from the metal box John saw.
Now the plutonium is in the hands of the Ukranian forces, who will be moving it in a week. John wants to kill Andrei but Priya tells him to wait until they can learn what’s going on since it seems the present is being attacked by the future. Afterward John meets with Kat and tells her the drawing has been destroyed, so now she must arrange the meeting with Andrei.
That night John is invited to a dinner party and he finally meets Andrei, who thinks John is having an affair with Kat. He threatens John and signals the guards to take him away, however John mentions opera and Andrei agrees to a private meeting the next day. In the morning Andrei reveals to Kat that his men retrieved the drawing before the fire reached it, so he still has power over her.
Then they go sailing with John, who shares his knowledge of the plutonium box to win Andrei over. During a sudden turn of the boat, Kat releases Andrei’s harness to make him fall, but John needs him for the plan so he dives in to save him. Later at Andrei’s yacht, John gives Kat a gun so she can protect herself.
Then he and Andrei discuss a plan to steal the plutonium back. Andrei shares that he grew up in a war zone and worked retrieving plutonium from scattered warheads. Inside a very peculiar drum, he found several bricks of gold and some pages of instructions with his name.
Thanks to those instructions he became the successful man he is now. In the evening, Andrei throws some things at Kat for what she did and gets ready to beat her up, but Kat points out her screams would make John want to save her and Andrei would have to kill him, so Andrei stops himself. At that moment a helicopter lands on the yacht’s and the workers bring out a huge heavy package.
John sneaks around to spy on Andrei opening the package, finding inverted gold bars inside. There’s one missing and an employee reveals he has it, so Andrei beats him up to death. Then a guard finds John and beats him up too before taking him to Andrei, who now is suspicious of him but still keeps the deal.
He gives John some gold and tells him not to contact him again until he has the plutonium. John convinces him to let Kat make the exchange when the time comes. On the day of the plan, Andrei brings Kat to a warehouse where they look at his inverted weapons.
Kat is nervous and Andrei yells at her, causing her to reveal her gun in fear. Andrei immediately responds by beating her up. Meanwhile John and Neil follow the truck moving the plutonium surrounded by security cars.
Andrei has provided a team that surrounds the truck with other big vehicles, including a firetruck. Drssed as a fireman, John climbs on the firetruck’s aerial ladder while the other vehicles begin crashing against the security cars to stop them, keeping the main truck trapped among them. Andrei’s men also block the truck’s radio so they can’t ask for help.
The ladder moves and puts John above the truck, where he uses a light explosive to create a hole in the roof. He jumps inside the truck and blows up the safe door to finally get the case with the plutonium box. Then he climbs out at the same time a police car starts to follow them, but Andrei’s men shoot it to stop it.
Now John can safely climb back into Neil’s car. The duo almost gets to escape, only to hear speech being spoken backwards in the radio. A vehicle ahead of them suddenly starts moving strangely and they realize Andrei wants to steal the plutonium from John instead of keeping the deal.
The inverted car moves backwards next to theirs and starts chasing them, getting close enough to show John that Andrei’s keeping Kat hostage. As a silver car on the road also starts moving backwards, John throws the case to Andrei to save Kat. Next Andrei jumps into a different car with the box while Kat stays in the first vehicle, which now has no driver.
Kat manages to open the door and Neil drives right next to her so Andrei can make a risky jump, getting into Kat’s car to make it stop right before it crashes. Andrei got to escape but more of his thugs arrive and open fire. While Neil shoots back at them, some men sneak around and kidnap John and Kat.
Afterward John is taken to the warehouse, where there’s another room split in two by a glass wall. He watches how Andrei and Kat appear on the other side moving backwards and since Andrei is speaking in reverse, a machine replays his speech in the right order. Andrei threatens to shoot Kat if John doesn’t tell him where he put the plutonium box because he only threw the empty case at him.
At first John refuses to talk, but Andrei reverse-shoots Kat so John confesses he hid it in the glove box of Neil’s car. Suddenly another Andrei appears on John’s side and starts hitting him, asking for the real answer because he knows John's lying. At that moment a bunch of soldiers enter the room and open fire, so both Andrei run to hide in the turnstile.
Now the Andrei from John’s side appears on the opposite side to complete the loop. Everything that just happened happens again, now in reverse to finish the timeline. After this Andrei is also gone, Neil arrives saying the soldiers work for Priya and Tenet.
A furious John pushes Neil and demands to know why Andrei knew all their moves, suspecting Neil of double-crossing him. However soldier Ives explains that what Andrei did is a "temporal pincer movement". This means that half of Andrei's men move forwards through time to act out the operation and then give the other half the knowledge of what happened.
That second half then inverts themselves and complete the operation successfully, creating a self-informed loop. The soldiers can’t help Kat because she has an inverted wound, so John wants to take her through the turnstile to invert the effects, pointing out he can use the machine in the freeport to return to normal later. The whole team takes Kat through the machine and they appear on the other side as they see themselves through the glass.
Now that they’re in the past, John wants to use the chance to try to save Kat from getting shot at all. Soldier Wheeler gives him an oxygen mask and advices him to wear a SWAT uniform to cover his whole body, explaining he shouldn’t see his other self or that would instantly kill them both. Then John leaves the warehouse and has to get used to move in an inverted world since everything here is backwards for him from air to gravity.
He gets in the silver car he saw earlier and drives to the shoot-out scene, where he finds the empty case by the road. John puts a microphone in it and hides to watch how the case jumps back to Andrei when he drives by. John starts following while listening to Andrei talk to his men, learning they already checked the glove box and know he was lying.
As he drives closer, he watches his other self receive the case and the plutonium box that is hiding in the silver car flies back into the case as well. It turns out John threw it there the first time. Andrei sees this second John and moves his car to make him crash, then he lights the leaking gas on fire.
Huge flames cover the car and an explosion knocks John out. Moments later John is shocked to wake up in the back of a truck with Neil and Kat. He learns that since he had been inverted, the effects of the explosion were nullified and it gave him hypothermia instead of burning him.
John starts interrogating Neil because obviously he knew everything from the beginning, however Neil promises to tell him who hired him later. John remembers that he heard Andrei mention something called “algorithm”, so Neil explains it’s a device made to invert the entire world and make it end. Sometime later, the truck stops at the Oslo freeport, where Mahir is crashing the plane.
Neil and John cover their bodies with uniforms and move a sleeping Kat on a stretcher toward the building. When John looks for an entrance, the engine explodes and pushes him through a door, revealing he was the SWAT guy that found his other self. The whole fight happens again but since it’s now in reverse, it’s show John is trying to get away from his other self by doing as little damage as possible.
They make it to the turnstile room and after shooting the glass, John jumps into the machine to invert himself back to normal. He appears on the other side and runs away, that’s when past Neil chases him and takes off his helmet. Seeing John’s face is why past Neil let him go.
Then John opens a door for Neil and Kat to come inside while he steals a van. Neil is careful to avoid his other self and successfully gets in the machine, inverting himself and Kat back to normal. They escape in the van and now Kat can recover normally.
Sometime later, John visits Priya and tells her he knows the box he had to steal had the algorithm. Priya explains that in the future a scientist creates the inverting method but fears that it will be used for war. Therefore the scientist breaks the algorithm into nine pieces and sends them to the past to keep them safe.
One of those pieces is the plutonium box, and now Andrei has all nine. The armies in the future chose Andrei to destroy the world and sent him instructions in the metal drum he found as a teen. Priya had planned for John to steal the box and lose it to Andrei on purpose so he would bring out all the pieces for his plan, this way her team can take them all back together.
John agrees to help them. A few days later on Priya’s ship, John and Neil explain to Kat that they can’t kill Andrei yet because his death activates the algorithm and the end of the world. Kat explains Andrei probably intends to self-delete because he’s dying of cancer.
If he doesn’t get to live, then the world doesn’t either. John convinces Kat to go back to Andrei and keep him distracted so the team can secure the algorithm before Andrei dies. Afterward John, Neil, and Ives’ team get reversed using Priya’s machine and start training how to fight like this for the incoming mission.
Helicopters take the team to the Soviet city where Andrei grew up since they’ve deduced the algorithm will detonate there. Ives explains the plan to everyone in detail: there’ll be an inverted blue team and a forward-moving red team, meaning they’ll try to pull off a temporal pincer to pass each other information. Neil and Wheeler are on the blue team while Ives and John are red, but the two of them will split to retrieve the algorithm.
At the same time, Kat waits for her other self to leave Andrei’s yacht and sneaks aboard to find Andrei. He already has poison ready to self-delete, so Kat tries her best to keep him distracted. Soon both teams make it to the abandoned city and start fighting Andrei’s army.
Each team sees the other as moving backwards, but they stay coordinated thanks to their watches. Both sides start losing soldiers as they desperately shoot at each other and inverted explosions keep bringing down or putting together random buildings. When the watches on both teams match in time, Wheeler’s team makes a huge explosion that acts as a distraction for Ives and John to sneak inside the underground base.
Outside, Neil notices an enemy coming out of the tunnel in reverse and leaving in a helicopter after setting up an explosive. Worried, Neil separates from his team and enters an old building, where he finds the machine used by Andrei’s team. Neil inverts himself too and gets on a truck to warn the other team but it’s too late, the tunnel has been sealed by the explosive.
Underground, Ives and John find a closed gate and a blue soldier dead on the other side. John is shocked to see the same red string on the backpack. At that moment the soldier that Neil saw appears and leaves a radio so Andrei can monologue at John about the end of the world while he gets the algorithm ready.
At that moment the dead blue soldier starts moving because he’s reversed and gets shot by the enemy when he tries to shoot John. His falling body pushes the gate open and John jumps on Andrei’s soldier to stop him from detonating the algorithm. A fight ensues and after exchanging some punches, John manages to push the soldier off the platform to his death.
On the yacht, Kat notices her other self is coming back on a boat and panics, so she shoots Andrei and throws him into the sea. Then she jumps too and gets rescued by Mahir before she can be seen by her other self. Thankfully John and Ives have retrieved the algorithm and Neil throws a hook into a different tunnel to bring the duo and the algorithm out right before the bomb activated by Andrei’s death explodes.
Once it’s all over, Ives breaks the algorithm in three so he, Neil, and John each take a part to hide in different places. After Ives leaves, John notices the red string and realizes Neil has been helping him all along. Neil finally reveals that John is the one that recruited him in the future, in fact the entire Tenet plan since the beginning has been John’s.
Now Neil must return to the timeline in which he dies by the gate. Sometime later Priya is in London with a guard, ready to kill Kat. However John appears and kills the guy first.
John tells Priya that they’ve been both working for his future self and kills her too. Then he watches Kat finally be happy with her son.
