John Greer falls asleep watching TV. He wakes up in his car with a bloody knife beside him. He drives to the police station, where he tells them he might have killed someone. Police go to his in-laws' house where they find his in-laws stabbed. Police tell John's wife Lisa that her mother has been murdered by John. She can't understand it. John has never been violent, and he loved her family. John can't explain what happened. The police have a strong case. John's father-in-law had identified him as the attacker, the murder weapon was found in John's car, and John had confessed.
Marlys Edwardh, John's attorney suspects that John may have been sleepwalking. An expert sets up a lab in a parole office to monitor John's sleep. His patterns of sleep indicate that he could have sleepwalked. John's grandfather had been a sleepwalker too. His family had learned not to wake him otherwise he would become aggressive.
Some of the factors leading to a sleepwalking episode are family history, stress, and fatigue. Previously, he had embezzled money to pay off gambling debts. Now, no one would hire him. He continues to steal money, this time from Lisa. When she finds out, she confronts him. He doesn't sleep the next few nights because he is worried she will leave him. Lisa figures out a plan to repay their debts and start over, but it means he will have to inform her parents. He is willing to lose his in-laws' respect if he can keep his marriage.
He falls asleep in front of the TV that night. A few hours later, he gets up and begins to act out the following day's events. He drives down the highway to his in-laws' house and enters. The rest is speculation. His mother-in-law tries to get his attention when she sees him, and he becomes aggressive. She gets a knife. John's father-in-law wakes up with John choking him. John grabs the knife by the blade and attacks his mother-in-law. The next thing he remembers is waking up in his car.
If John did sleepwalk, can he be guilty of murder? Did he program himself to carry out these actions in his sleep? The jury finds John not guilty.