Ashley is a tour guide at PAST TENSE, a company that sends camera drones into the past to view history's most depraved events. When Ashley discovers Silas Green, an unknown serial killer working in the past, she begins hosting "exclusive" tours of his murders. The only problem? Silas is still alive in the present. And when he learns of his newfound infamy, he is inspired to come out of retirement to make Ashley his final victim: Now and forever.