The film focuses on a panic room, a safe shelter usually located inside a residence. The panic room in this film is protected by a four-inch-thick steel door and an impressive security system, and features a phone line not connected to the residence.

The residence is 38 West 94th Street in Manhattan, a four-story townhouse that was previously owned by a disabled reclusive millionaire. Following the owner’s death, the house was bought by Meg Altman (Foster), a woman, recently divorced from the owner of a pharmaceutical giant, who is planning to go back to college.