Yoon Bum is a scrawny, awkward man who suffers from mental illness and has an unhealthy romantic fixation with popular college student Oh Sangwoo. He’s taken to stalking the object of his obsession, even going so far as to break into Sangwoo’s home; but the horrors he discovers in the young man’s basement are beyond his darkest nightmares. His would-be prince charming is actually a serial killer, and when Bum is caught trespassing, he soon learns that breaking into a psychopath’s house is a lot easier than getting out…