On Christmas Eve, an ambitious young executive, Angela Bridges (Rachel Nichols
), works late before she leaves for her family's holiday party. When she gets down to the deserted parking garage, she discovers that her car won't start and she can't get a telephone signal on her cell in the underground.
A friendly security guard, Thomas (Wes Bentley), comes to Angela's aid. She nervously accepts his gesture of goodwill to help her with her car. Soon after a failed attempt to start her car, he invites her to stay and share a small Christmas dinner he's preparing in the parking office, but she laughs it off. Angela doesn’t realize this is no laughing matter -- Thomas has been watching her closely...for months. His dinner invitation is not optional. If Angela wants to live to see Christmas morning, she must find a way to escape from level P2 of the parking garage.