Mother Father Sister Brother Frank

Frank discovered that Jerry and Joy allowed someone to launder money through their travel agency, which had been struggling for a decade. Using this knowledge, he blackmail them and demands both the house and the $5 million they earned from the laundering operation.

Earlier, Joy and Jerry argue about when to share their own news, hinting they are keeping a secret from the children.

When Jolene offers Frank the money in exchange for leaving the house, he admits his true motivation is envy and resentment toward Jerry for over 30 years. The money is secondary, he wants to destroy his brother out of long-standing jealousy.

Frank is immediately antagonistic upon arrival, making rude remarks about everyone, suggesting personal animosity rather than just financial gain.

Jolene first drugs Frank with Lorazepam by putting it in the banana breeze pie he eats. Then Joy smashes a lamp over his head, Jerry tries to strangle him, and Joy finally pushes him down the stairs. Frank dies after colliding with the pie tin, which lands on his face.

Frank says he would only back down over his dead body, planting the idea of killing him in both Jolene's and her parents' minds.

Jolene attempts to negotiate with Frank first, offering him the money if he leaves the house. When that fails and Frank reveals his true motive is revenge, Jolene decides to disable him by drugging his pie with Lorazepam to make the physical attack easier and reduce his ability to fight back.

Jolene is established as pregnant and protective, she wants to handle the situation before it endangers her or her family further.

After being weakened by the Lorazepam-laced pie, Frank is attacked by the family: Joy hits him with a lamp, Jerry tries to strangle him, and Joy pushes him down the stairs. He dies from these combined injuries when he lands on the pie tin, which ends up on his face.

The family needs to dispose of Frank's body completely to avoid detection. Jim takes on the task of dismembering the body in the basement so they can freeze some parts and burn the rest, making it easier to eliminate all evidence of the murder.

When the officer arrives for a noise complaint and sees suspicious details like tarps and the neighbor's dog carrying an arm, Joy gives a bizarre non-confession that explains nothing truthfully. Pete then convinces the officer not to call backup and offers him a ride home, buying time for the family to continue cleaning up.

Pete arrives during the chaotic aftermath and initially causes a scene, but Jolene lets him stay to prevent him from disturbing the neighbors further. Once inside, Pete helps distract the police officer and convinces him not to call backup. He later implies he expects the family to owe him favors, hinting at future leverage.

After Frank's death, Jolene slips on his pool of blood while running upstairs after seeing her parents have sex. This accident causes her pregnancy to be revealed to everyone before she had made a decision about keeping it, which annoys her.

Earlier, Jim discovers Jolene is pregnant in the upstairs bathroom but agrees to keep it secret until she's ready.

After successfully killing Frank and eliminating the threat to their home and money, Jerry and Joy feel a rush of relief and adrenaline. They sneak off together and have sex, which Jolene unfortunately witnesses, adding to the family's already disturbed state.

The ending shows the family working together to strip walls, scrub floors, and dispose of Frank's body parts. They grow closer through the shared secret and crime, achieving a twisted unity. However, Pete's hint that they'll do "another murder mystery" suggests the family has crossed a moral threshold they can't return from.

Jim reveals to Jolene during the dinner that he is divorcing his husband Pete. The specific reasons for their marital breakdown are not detailed in the film, but Jim deflects when Jolene asks about Pete, suggesting the divorce is already contentious.