Till Death (2021)

Emma is unhappily married to her cold and controlling husband, Mark, who works as a criminal attorney. After ending her affair with Tom, a partner at her husband's firm, Emma goes out with Mark to celebrate their anniversary. Mark surprises Emma with a necklace made of steel and drives her to a secluded lake house, which they used to visit early in their relationship. That evening, Mark apologizes for his past behavior, and they make love.

The next morning, Emma wakes to find herself handcuffed to Mark, who abruptly commits suicide by shooting himself in the head. Forced to drag his corpse everywhere she goes, Emma discovers that Mark destroyed her phone and removed every sharp item from the house. She eventually finds the keys to their SUV and reaches the garage. When she tries to start the vehicle, the engine won't turn over, and she sees that Mark has siphoned out the gas tank. The car's audio plays a taunting message from Mark that reveals that he knew of her affair with Tom.

Hours later, Tom arrives at the lake house. He tells Emma that he was summoned by texts from her phone and that Mark was facing disbarment for illegal activities at his practice. They both realize that Mark sent the messages to lure Tom just as a mysterious truck is seen approaching the house. Emma hides while Tom greets a man named Jimmy from the truck. Jimmy says that he is there to fix the plumbing and refuses to leave, despite Tom's attempts to dissuade him. Jimmy's brother, Bobby, gets out of the truck and stabs Tom to death. It is revealed that Bobby was a stalker who once attacked Emma and just got out of prison after he served 10 years.

Emma manages to evade the men and makes it to the boat shed. She uses an anchor to cut herself free from Mark's corpse and hides just as the men enter the shed. Emma overhears them reveal that Mark hired them to kill her and that they must find the diamonds that they were promised. Bobby suspects the diamonds are in the bedroom safe, which requires Mark's fingerprints and a code that Emma would know.

As the men search the house, Emma finds a fuel can and tries refueling the SUV, but Bobby slashes the tires. Emma then makes her way to the attic and lures the men there. She knocks Bobby out with a golf club and locks Jimmy into a nearby room. She attempts to escape in Tom's car, but Bobby intervenes. Emma manages to dial 911 on Tom's phone before she is knocked unconscious. She later wakes up in the bedroom and is once again cuffed to Mark's body.

Bobby tells Emma the safe's code is the date that Mark proposed to her. When she refuses to cooperate, Bobby threatens to cut off her toes. Jimmy objects and points Mark's gun at Bobby. Emma agrees to reveal the code if she is set free first. Emma is uncuffed and tells them the code. Bobby opens the safe, only to find a hacksaw inscribed with a clue that implies the diamonds are in Emma's necklace, which has no latch and is impossible to remove. Bobby realizes that the necklace can be retrieved only by decapitating Emma. Jimmy tries wrestling the saw away from Bobby but is accidentally impaled on a coat hook, which kills him. Enraged, Bobby attacks Emma and stabs her in the leg. She manages to fight him off and cuff Bobby to Mark's body.

Emma makes it to Tom's SUV, with Bobby in pursuit. She hits Bobby with the SUV but crashes into the boat shed, getting the truck stuck in the snow. Emma exits the truck and fights Bobby on the frozen lake. She stabs Bobby in the shoulder just as the ice gives way. Mark's corpse falls into the lake and drags Bobby with him. Bobby manages to grab Emma and to pull her in as well. As they sink, Emma grabs the knife out of Bobby's shoulder and stabs him in the eye. Mark's body drags Bobby down to his death as Emma swims up to the surface.

Lying atop the ice, Emma removes her wedding ring and lets it roll into the lake as sirens are heard approaching in the background.