Crandall Cady is just an average family man who wants nothing more than to lead an average life. But a disk he discovers on a crowded sidewalk is about to change his average life forever. The contents appear to be a home video filmed four weeks from the day he discovers it, and the contents are of him.

The next four weeks are a countdown to zero, and to protect his family, Crandall has precious little time to determine if the recorded images are genuine or merely an elaborate hoax. As he begins to unravel the mystery behind the disk, he starts to question everything he has ever learned...