The movie starts at a construction site, where a successful contractor named Clint, enters his office, and makes a telephone call to his beautiful wife, Joanna. He tells his wife that he feels sad as she is leaving for the weekend, but he will get off work early to see her off, but we notice the wife seems annoyed by this. Clint is next shown tending to a visitor, while Joanna, back home, takes a parcel out of the mailbox while a dog continuously barks in the background.
The scene shifts to show Clint driving down a road, when he is stopped by a sheriff. Sam, the local sheriff approaches Clint, and asks if he would be interested in going fishing with him. Clint gives an open and honest assent, responding that since Joanna is gone for the weekend, he has a free spot available.
The sheriff then lets him go, and Clint immediately heads home. As soon as he arrives home, he opens the door for his dog, Duke, who has been yelping since nobody lets him out of his crate. Joanna doesn’t appear to be very pleased to see Clint there, and she confirms that she has received his message.
She also has to leave early because she has an appointment with a doctor. Interestingly, Clint informs Joanna that a buyer stopped by the workshop to make another offer of a million and a half to buy Clint’s business, but Clint decided not to sell it. Joanna comments that it is a lot of money, but Clint replies what would he do if he sells the business, to which Joanna answers angrily that they could go back to New York.
The discussion escalates to an argument, and Clint makes it clear that he travelled 2000 miles from New York to here to build a better life for them. A not-so-happy Joanna then leaves the house in her light blue car, which of course was provided by her husband, leaving Clint in despair. Afterwards, Clint goes out with the sheriff, and while they fish, Clint unloads some of his woes.
The sheriff asks how things are going back home, to which Clint replies that Joanna has been a city girl struggling to adjust. Meanwhile, it turns out that Joanna has been having an affair with her doctor, Cortland. The doctor tells her how she will own a clinic with him in Beverly hills, amongst other pleasures.
He also has extracted a toxin from the ovaries of a fish, and says that the recipient will have a cardiac arrest. They conspire to kill Clint and sell his company, and Cortland convinces Joanna to put it in Clint's food to kill him, and make sure that he takes all of it. When Joanna gets back to her house, she starts emptying her purse looking for the poison when the bottle spills and starts leaking.
She hides the poison in the laundry basket, and we can see that it is leaking inside. After Clint gets home later, he sees Joanna preparing a steak for him, and tells Joanna he’ll be out in his home workshop for a while. Stressed by the noise from workshop, Joanna begins remembering about the poison she had hidden earlier.
She goes to the trash and retrieves the bottle of poison, which she ultimately decides to add to the wine. However, Clint suddenly shows up, and brings the two glasses of wine to the dinner table. Joanna sits and watches Clint as he eats, worried about what might happen if she drinks from the wrong glass.
Clint picks up the wine and then asks her to do a toast with him. Unfortunately for Clint, he drinks the poisoned one, and as a result, his body starts to react to it and he has a cardiac arrest. The husband falls to the floor in pain, and screams for Joanna for help, but she refuses to assist him and instead urges him to end his life.
Joanna then calls her scandal doctor, Cortland, to let him know the job is finished. Later on, Sam the sheriff and Cortland arrive at the house. Sam is so upset and doesn’t expect that his friend will have a heart attack in his prime.
Here we see that the poison bottle ends up being on the ground, and Sam nearly steps on it. The sheriff then asks the coroner if they should conduct an autopsy, but Cortland says that there's no reason for it. The scene switches to a refrigeration room, with bodies stored there, one of which moves a little.
The next morning, Clint’s body is taken out of the bag by the coroners, and they start to prepare his body for the funeral. At the same time, Cortland calls the funeral home, and tells them that Joanna wants Clint to have a quick funeral without embalming. While this is happening, the workers from the funeral home are about to cut Clint’s body, but are stopped by the owner as they say that the family went cheap on them.
They choose a very cheap casket to put Clint in, and prepare for the funeral. During the funeral, the dog continues to behave strangely as Joanna approaches the casket to put her flower. She then proceeds to show her remorse by crying.
Later that night, Joanna is shown in her tub with Cortland; the two share a couple of drinks, and laugh about the murder they just pulled off. The night is marked by storm and thunder; Duke the dog begins to bark wildly looking for his owner. This annoys Joanna who says that she has had enough of the dog and takes out a gun to shoot it.
She holds a gun and breaks open the cage door with a gunshot, and as Duke runs out, she tries to shoot him but misses. Duke travels to the cemetery, makes his way to Clint's grave, and sits down next to it. But to our surprise, Clint is actually still alive underneath the coffin, and apparently, the effects of the poison have just worn off.
He feels water dripping on his face, and tries to get out of the casket. Panicked, Clint breaks the casket, which starts to break due to its poor quality. To our great relief, Clint is able to overcome the obstacles that stand in his way, and crawls out of his grave.
He is welcomed by the sight of his dog, and then starts to make his way home. The man is able to reach his front door and is still struggling to walk. He slowly makes his way to the side of the house, and to his surprise, he witnesses his wife kissing Cortland.
Now that he understands everything, he waits until Cortland leaves the house, before breaking the windows to his basement and entering it. Clint then tries to make his way upstairs, but he seems weak and falls down the stairs, so he decides to spend the night hiding out in the basement. The following day, Joanna meets Clint’s lawyer, who provides her with information regarding important documents that Clint possesses, as well as details regarding Clint's bank account.
She tells the lawyer that she is willing to sell the company for 1. 5 million dollars, with the payment due in 48 hours. Inside the basement, Clint finally wakes up and heads upstairs.
He first goes to the kitchen sink and drinks some water, then he moves to the fridge and takes something to eat since he is ravenously hungry. As he is eating, he notices his wife coming back in the car, and he hurries back to the basement, now with a gun in his hand. However, he drops the shells and has to go down the flight of stairs to grab them.
He manages to load the gun, and then heads on above to shoot his wife. However, the bell suddenly rings, and it turns out that the Sheriff has come around to check up on Joanna. The sheriff begins to reminisce how Clint built the house with his bare hands, and asks Joanna about the sales sign in front of the house, to which she replies that the place seemed small now that Clint had passed away.
The sheriff and Joanna also talk about her selling the business. As Sam proceeds to head out, Cortland has just arrived to meet his so-called patient, before making his way in. Upon seeing that Cortland is inside too, Clint realizes that he has just one bullet loaded, so he heads back to the basement.
Meanwhile, Joana begins to freak out over the sheriff's questions, insisting that they should leave the same night, but Cortland says that they should wait one more night, since the real money from selling the business would come the next day. The two also talk about how Joanna had been pregnant, and that she had aborted her baby so she would not have to stay with Clint. This angers Clint further, but he takes out the shells from his rifle, saying that killing them with a gun would be too easy.
Later that night, when Joanna has fallen asleep, Clint grabs scissors from the room. After cleaning himself up, he proceeds to disinfect his hands, and he places bandages over his wounds. Some people arrive the next day with a briefcase full of cash, signifying that the sale of the business is complete.
Joanna seems to be taken back by the amount of wealth in her hand, and after letting the businessmen go, she is beyond excited that she can spend the money with Cortland. Meanwhile, the sheriff hurries over to Clint's grave, where he discovers that it has been dug up and that the body is missing, assuming that someone had done it. The sheriff orders that the casket be sent to his home, and that everything should be kept quiet until he finishes his investigation.
Back at Clint’s home, as Joanna smiles brightly over the million dollars, she is aghast when she finds the bathroom with mud all over the floor. She then calls Cortland, who doesn't answer, so she leaves a voicemail warning that someone might be inside the house. Joanna then remembers to pick up the gun and proceeds to the basement.
She encounters Duke on her way there, and it starts barking at her while she slowly moves back and goes to pick up the gun. But just as she is about to shoot at the dog, Clint locks her in the basement, and goes around the basement, boarding up all the windows. On the other side of the story, Cort is talking to his fish while he moves to take more poison from them.
He then checks his messages, only to hear that his landlord is coming to kick him out because the previous six months' rent was not paid. When Cortland arrives at Clint's house, he takes out the syringe with the poison, as he continues to call out to Joanna. He first goes to her room and sees the briefcase of cash.
Meanwhile, Joanna finally wakes up and hears Cortland calling her name repeatedly. Thinking that he was the one who scared her earlier, Joanna hides under the stairs. She then hits him with a metal rod, dropping the poison injection out of his hand.
Joanna picks up the case and starts to head upstairs, but Clint shows up and shuts the door. Sometime later, Clint starts bringing wood into the house, while Cort has just regained his consciousness. Joanna apologizes for hitting him, and tells him that someone in the house has locked them down there.
Cort attempts to escape by trying to shoot at the locked door, but finds out that the man has disabled the bullets, and it is nothing but gunpowder and air. He then tries to break open a wooden window, but Duke begins to bark through it, so he eventually has to back off. Upstairs, it is revealed that Clint attempts to remodel the house; Clint continues to saw into the walls and destroys a picture of him and his wife.
When Joanna awakens the next day, Cort tells her that they've been stuck there for eight hours. Cort also wrongly assumes that the man upstairs is Sam the sheriff, who wants a piece of the pie. For whatever the sheriff has done to them, Cortland is eager to kill him now.
Just then, Joanna ends up seeing the poison injection underneath the drawer. Realizing that Cort had brought it to poison her, Joanna hides the syringe, and asks Cortland to burn all of the money if he truly loves her. Cortland refuses, so Joanna confronts him about the injection, and he admits that they will never have a clinic of their own.
As Cortland is about to inject Joanna with the poison, the door to the basement opens. The two decide to not waste the injection on each other, so they walk out through the door, only to find out the house has been remodeled with wood everywhere. They try to find a way through, but keep on getting stuck.
While trying to find a way out, they are led through a maze. On the other side of town, Sam the sheriff can't stop thinking about his friend's case. He tries to look at the casket again, and realizes that someone broke out of it, while trying to test his theory.
Back at Clint’s house, Joanna and Cort start arguing over the crime they committed, right when a wall emerges between them, separating the two. At the end of a passage leading to an unblocked window, Cortland sees a shadowy figure. Thinking it's Sam, Cortland tries to bribe him with all the money.
But then, Clint reveals himself, causing Cort to trip on the briefcase of money and fall on the syringe, injecting himself with the poison Shortly afterwards, Joanna is trapped between Clint and a small hatch. She crawls through the hatchway along a low passage to where it suddenly dead-ends, allowing Clint to shut her inside. Clint finally reveals himself to her, and mentions their aborted child, asking if it was a boy or a girl.
He then dumps the dead Cortland and money inside what is now a large wooden coffin, and nails it shut. Up next, he proceeds to pour gasoline all over the place, and uses a flare to set his house on fire. He puts the large box on his truck and doesn't forget to bring along his loyal dog.
Soon after, Sam arrives at the scene, and after the fire is extinguished, no bodies are found. When Sam visits the cemetery again, he sees a man standing at Clint's filled-in grave, and has a little chat. Realizing that it is his friend Clint, Sam tells Clint that he doesn’t know him, and doesn’t want to see him here ever again.
Clint understands this and gets in his truck to leave. Before the film ends, it is revealed that the still-alive Joanna, the dead Cortland and the money all now occupy Clint's grave, with Joanna hopelessly screaming for help.
