William controls the car remotely and uses built-in tasers in the seats to shock Eddie whenever he talks back or swears. He also manipulates the car's temperature, alternating between freezing and overheating Eddie. The car is soundproof and heavily modified to prevent escape, including bulletproof glass and remote locking mechanisms. Eddie is subjected to physical violence from the car's movements and environmental torture such as lack of food and water, pushing him to desperation like considering drinking his own urine.

Eddie injures himself multiple times: he cuts his forearm by striking the car's interior in panic, and when he shoots at the bulletproof glass, the bullet ricochets and hits his leg, causing a severe bleeding wound. These injuries contribute to his physical deterioration while trapped inside the car.

Eddie is a desperate father who cannot afford to repair his van and struggles to pick up his daughter Sarah from school. His motivation for stealing the car is partly driven by his desire to provide for Sarah. Throughout the ordeal, Eddie apologizes to Sarah over the phone, showing his concern and regret. After the climax, Eddie reconciles with Sarah and buys her a bicycle as a replacement for his broken van, indicating a renewed commitment to their relationship.

William is a wealthy doctor in the late stages of cancer who has lost his daughter to street criminals. Motivated by grief and a desire for vigilante justice, he has modified the Dolus SUV as an elaborate trap to punish thieves like Eddie. William's actions are driven by trauma and a need for closure, though he is portrayed as lacking empathy and more of a vindictive figure than a sympathetic one.

Towards the end, William and Eddie come face to face. William coerces Eddie into a dangerous drive during which they argue and taunt each other. Eddie finds the car's power-off button, and when he meddles with it, the car moves forward and falls off a cliff. Eddie manages to escape the crash, but William dies in the accident. This confrontation leads to Eddie's survival and eventual reconciliation with his daughter.