Neurologist Sejin discovers a man, Lee Taesoo, miraculously alive after a horrific accident—with a steel pipe lodged in his head. Seeing him as a perfect test subject, Sejin saves him, only to find Taesoo suffering from amnesia. In exchange for his recovery, Taesoo demands help in regaining his lost memories. But as Sejin observes his unnaturally fast healing, strange phenomena begin to unfold, setting off a series of unpredictable events.