It is the last night before Tanglewood Memorial closes for good, and MRI technician Mike Hughes arrives for his final shift at the hospital. Between the bare-bones staff and the fact that all the patients have already been moved to the new facility, Mike is prepared for a quiet night. All that changes when a special patient arrives, complete with a five-man police escort: the infamous serial killer Frank Snow has been brought in for a brain MRI. As if that's not enough, Mike's wife Sarah decides to drop in unexpectedly, along with their young son, Eli. Then Snow unexpectedly breaks free, cuts the power, and locks the doors. Now he's loose in the old, dark hospital, hunting its last occupants one by one, and escape seems to be the furthest thing from his mind.