On a planet four solar systems away from our own, there’s a race of men who have advanced beyond the human limits. Instead of breeding they produce clones, which has caused their reproductive organs to shrink and disappear. Emotions have been bred out of this society and each new generation is more ambitious, so now they want to take over the universe.
The leader Graydon announces they’ll start by conquering Earth from the inside by impregnating human women to make their own babies. The men get special training in which they watch a hologram of a woman to learn how procreation works and what holes must be used. They’re also taught to talk about things like shoes and to give women plenty of compliments.
A hologram of a woman plays for several minutes and the men are taught to often say “uh-huh” so she knows they’re listening. They do date simulations and speedrun to see who can get coitus the fastest, believing one compliment and a glass of wine is enough. Whenever they celebrate, they stomp their feet instead of clapping.
The first man chosen for the mission is given the human name Harold and a robotic reproductive organ before he leaves. On Earth, two pilots notice something strange on the radar before the plane starts shaking. They think they’re about to crash, however the plane is only hit by two bright lights.
The passengers are thrown off their seats but everything quickly returns to normal. In the bathroom, Harold and Graydon have appeared. Harold says he only needs two days, and Graydon reminds him to come back after getting the baby before disappearing down the toilet.
Then Harold comes out and tries hitting on Rebecca the stewardess, who threatens to report him if he doesn’t go to his seat. He sits next to a woman in the middle of a panic attack yet tries hitting on her anyway, quickly giving up when she starts talking about her husband. Moments later when the plane lands, a car appears on the runway and hits the carts.
The driver Roland doesn’t apologize because he’s an inspector for the Federal Aviation Administration or FAA. While Roland asks for details about the incident, Harold tries hitting on Rebecca again and she slaps him. On her way out of the airport, Harold tries with another woman that insults him and ignores him, then with a woman asking for donations.
He causes her to drop her can and when she bends over to pick it up, her rear makes Harold excited. A bulge appears on his pants and a whirring sound can be heard from the robotic member activating. Harold keeps smacking it while trying to flirt with the next woman, which only makes him look like a creep.
Afterward Harold goes to a bank where he’ll start his new job. He’s welcomed by Perry, who immediately admits he’s doing the dirty with most female coworkers. Harold asks Perry to take him women hunting right now, but they’re interrupted by their boss.
The man is very impressed by the fake recommendation letters the aliens made up and Perry is already annoyed that Harold is liked more. Meanwhile Roland keeps paying little attention to his wife’s calls even though she wants him to know she feels neglected. Roland watches a video a man took on the plane during the incident and he’s shocked to see some bright lights before static takes over the screen.
After work, Perry takes Harold to a naughty club and he hires a worker. They go to her room to do the dirty but first she asks him to put on protection, however the mechanic member sends the rubber flying and the woman cancels the night. The next day, Perry takes Harold to an Alcoholics Anonymous meeting, explaining the women here are easy because they’re vulnerable.
When Susan takes over the mic to share her story, Harold immediately becomes interested on her. After the meeting, Harold tries to talk to Susan, but he’s found by Rebecca first. While they chat, Susan tries leaving only for Perry’s car to hit hers.
An argument ensues and she demands his insurance information to settle this. Moments later, Harold is trying to do the dirty with Rebecca and she keeps getting annoyed by the whirring sound. They’re interrupted by a call from Rebecca’s boyfriend, who is a married pilot.
Harold makes an inappropriate comment and an angry Rebecca kicks him out. The next morning Roland eats breakfast in a hurry because he’s excited to go to work and keep investigating the incident. His wife thinks he’s cheating on her and Roland tries explaining that something supernatural happened with a plane, which she thinks it’s a bad lie.
At the bank, Harold and all the workers can’t stop staring when Helen comes in. Harold gets ready to hit on her, only to learn she’s Perry’s wife. Then Susan arrives looking for Perry to settle the car bill and Harold tries flirting with her instead, however Susan quickly realizes he’s one of those guys that goes to AA meetings for the vulnerable women and calls him disgusting.
When she gives Perry the bill, Helen overhears that he was at an AA meeting last night so Perry pretends he has a drinking problem to cover up his infidelity. Afterward Harold tries with Susan again and at first she says no, but he insists and she’s so desperate that she ends up accepting a dinner invitation. In the evening, they go to a restaurant and Harold lets Susan talk for hours while only occasionally saying “uh-huh”.
When Susan asks him what’s his mission in life, he says he was put on Earth to have a kid and Susan gets emotional because men usually don’t want commitment so soon. As Harold’s groin starts whirring, Susan admits she has trouble trusting men. Afterward they go to her apartment and Harold rushes to her bedroom without even asking.
He then starts kissing her, however Susan pushes him off and explains she’s trying to fix her life, so she won’t do the dirty anymore until she gets married. Panicking, Harold leaves. The following day Harold shows up in a plane’s bathroom to meet with Graydon, who tells him to get married to Susan for the sake of their plan.
Meanwhile Roland interviews Rebecca about the incident and she tells him about Harold’s weird behavior, realizing she hadn’t seen him aboard before the lights. She also comments on the whirring sound. When Roland checks the list of passengers, he can’t find Harold’s name.
At the bank, Susan looks for Harold to open an account and Harold surprises her by asking her to marry him. Susan is speechless and asks for time to think about it. Later while she’s showing a house to potential buyers, she realizes she wants a marriage and a house like theirs.
She discusses the issue with her friends over lunch and concludes she’s running out of time. That afternoon, Susan calls Harold and agrees to marry him. Harold immediately begins organizing things and asks Perry to take care of his clients while he takes a few days off.
The couple has a private wedding in a small chapel and Susan shares a beautiful speech, but Harold only says one sentence. Once they’re officially married they go to their hotel room and Harold finally gets to do the dirty. Because his member is mechanical, he can keep going without getting tired and keeps Susan in bed for days.
Eventually she becomes exhausted and convinces him to visit some touristic attractions, which he doesn’t enjoy. In the meantime, Perry takes credit for Harold’s work and convinces his boss that Harold is some sort of creep. When Harold returns to the office, he finds Roland inspecting his office.
Roland asks Harold about the flight while putting a naughty magazine on the desk. Harold’s groin starts whirring so he sharpens a pencil to cover up the noise. At home, Susan is telling her friends about Harold’s strange member and they find it amusing.
When Harold arrives, he barely says hi and rushes to the bedroom. Susan comes after him and calls him out for his manners, however Harold only wants to know if she’s pregnant yet. This makes Susan feel ignored and Harold tries to assure her he cares, so she hugs him and makes him whir.
Sometime later Susan tries another pregnancy test and is negative again. Harold gets annoying about the subject and Susan feels like he only values her for her womb. Harold continues to make clueless comments and causes Susan to snap, so she goes on a rant on how she needs more from this relationship to make it work.
She asks for some comfort and has to teach him how to cuddle her, but he still tries to make it dirty. Susan snaps again and says he should be more human, causing him to panic and run away. Soon Harold meets with Graydon on a plane bathroom again and says he wants to quit the mission.
Graydon forbids him and tells him that if Susan is being difficult, then he should get a different woman pregnant instead. Meanwhile Roland is gathering alien drawings because he thinks Harold is one. When he goes to the airport, he gets a call telling him about another plane seeing the same lights and with the same Harold aboard.
That night, Harold goes to a bar and tells an old lady that he’s an alien while drinking. However the woman drinks too much and passes out. At that moment Helen arrives and chats with Harold, finding him amusing.
Soon his groin starts whirring and Helen invites him to her house while Roland watches from afar. The couple tries to do the dirty, however the whirring stops and Harold is unable to perform. He goes to the bathroom to smack it into working and Roland appears at the window to take a picture of him.
Harold panics when he hears a noise and tells Helen he can’t do this, so she explains he must be feeling guilty over Susan. When Harold gets home, Susan welcomes him with a song and announces she’s pregnant, so they reconcile with a hug. The next day he’s in such a great mood that he doesn’t mind finding Perry getting dirty with another employee in the vault.
He hears from his boss that the promotion is being discussed for either him or Perry, so Harold sends the man to the vault to make him see the truth. Meanwhile Roland is listening to the radio and learns from the news that the power balance in the Middle East is changing because one country is having more children than the other. This makes him wonder if that’s the aliens’ strategy too.
At that moment his wife announces she’s leaving him because she found the picture of naked Harold, so she thinks Roland is in the closet. Roland tries to explain his whole alien theory and his furious wife leaves the house. The next day Perry tells Harold that he thinks Helen is having an affair.
Harold plays innocent, however Perry quickly accuses him of doing his wife and snitching. When Harold reminds Perry that he stole his work, Perry becomes offended yet quickly drops his attitude to follow another woman into the vault. As days pass, Susan notices that Harold doesn’t want to do the dirty anymore and spends all his free time watching TV.
He ignores her when she tries to talk about the issue, so she throws the remote at the wall, breaking it. Harold wants to leave to buy a new one and Susan has to remind him they have plans to go shopping for the baby, however Harold leaves for the electronics shop anyway. Sometime later they go to the doctor and Harold keeps talking about the remote while Susan gets an ultrasound.
The doctor freaks out when he sees the screen because Susan assures him she’s been pregnant for only six weeks but the fetus looks five months old. Susan is worried, but Harold rushes her home and reminds her that what matters it’s for the baby to be healthy. The next time Harold goes to work, he’s disappointed to hear Perry got the promotion.
He suddenly snaps and yells at Perry, saying he’s probably doing the dirty with the boss too. Perry insults him and Susan, so an angry Harold punches him. Later he shares the story with Susan, who explains frustration is only human and points out he’s crying.
Harold is surprised since he isn’t supposed to feel anything and finally apologies to Susan for his behavior the last few days. They share a kiss and his groin whirs, so they get dirty at last. A few weeks later, the couple buys a house for their new life together.
On Christmas morning Harold surprises Susan with a crib, but the moment is interrupted when her water breaks and Harold has to drive like crazy to take Susan to the hospital. Meanwhile Roland tries telling his bosses at the FAA about his alien theory and takes them to Harold’s home, only to hear from the neighbor about the baby. Soon Susan is giving birth surrounded by a dozen specialists because of her unique situation.
She worries because she doesn’t hear the baby cry, but the doctor assures him the boy is healthy and puts him in her arms. Harold’s happiness drops when he sees Graydon watching him outside the room. Later while the baby is in the delivery room, Harold informs Susan that he must leave and won’t be coming back.
Furious, Susan yells at him and makes the nurse take him away. By the time Roland arrives with his men, Harold is already gone. Guessing that Harold is going back to his planet, Roland rushes to the airport and searches for a flight with Harold’s name.
He boards the same plane and tries following him to the bathroom, but a passenger blocks his way. Suddenly the lights hit the plane and make it shake, so when Harold finally reaches the bathroom, Harold is gone again. Afterward his bosses force him to take a sabbatical, saying he’s gone crazy.
At the hospital, the doctor gives Susan a sedative before dropping bad news: her son has disappeared. On the alien planet, the men are going through a new training program based on Harold’s experience. The hologram is now based on Susan, so when Harold has to teach them how to deal with certain situations, he looks at her face and feels guilty.
Suddenly he turns the hologram off and tells the men that Earth is full of conflict but that’s a good thing because it helps people learn more about themselves. He also questions why they must conquer Earth and give up emotions, so Graydon orders the guards to drag him away. On his way out, he’s shocked to discover the aliens have kidnapped his baby.
Afterward Graydon scolds Harold in front of everyone and reveals they’ve taken care of the woman at the bar because Harold told her he’s an alien. When Harold questions the system again, Graydon announces he’ll be sent to the purification center. The guards drag him away again, but this time Harold knocks them out.
He immediately runs to rescue his baby and triggers an alarm, causing more guards to come after him. Soon he’s surrounded by armed men, however they step back when the baby starts crying. They ask Harold to turn him off, so Harold starts making up lies about the power of babies to scare them more.
Then the baby starts peeing at the men’s faces and they run away in panic, allowing Harold to touch the teleporter and appear on another plane. At home, Susan and her friends are making missing posters for the baby that have Harold’s face as the kidnapper. At that moment he shows up and finally remembers the friends’ names.
Susan immediately takes her son back and asks her friends to take care of him so she can talk to Harold in private. Harold tells her the whole truth but she doesn’t believe him and tries to call the police. Desperate, Harold makes a bright light appear on his nose while Roland watches from the window.
Susan has a breakdown while Harold apologizes, saying he doesn’t understand what love is. Then he kisses her forehead and leaves. Outside Harold bumps into Roland, who asks him to come home and show the light to his wife so she'll believe him too.
At that moment Graydon blocks their way and threatens them with an alien weapon, however Roland quickly kills him with a normal shot. Then he takes the body with him as he leaves to prove his story to the world. Suddenly Susan comes out and tells Harold she doesn’t know what love is either, so she wants them to learn together.
The couple then reconciles with a kiss. A few days later they have a proper wedding ceremony with friends from both planets. Roland attends with his wife because they’re doing better, and Perry is with both his wife and his mistress.
This time Harold has prepared some beautiful words for his vows, and the happy kiss causes all the aliens to start whirring. On their way to their honeymoon, Harold announces the aliens want him to be the new leader and proposes to live on the other planet. However Susan wants the baby to have a normal life and forces him to commute.
