They're calling it the worst pile-up in London history. Driving home, Margaret Holloway has her mind elsewhere when she's rear-ended and trapped in the wreckage. Just as she begins to panic, a disfigured stranger pulls her from the car just seconds before it's engulfed in flames. Then he simply disappears. Though she escapes with minor injuries, Margaret feels that something's wrong. Flashbacks to the crash are dredging up lost associations from her childhood, fragments of events that were wiped from her memory.