Kai (Leehom Wang) awakens on his Shanghai houseboat––alone. His girlfriend Emma (Olivia Munn) has suddenly disappeared, leaving behind the one thing that could lead to her whereabouts: her smartphone. Deeply disturbed, Kai seeks to uncover where she went, with whom she's connected, and what she took with her. Is Emma really who she says she is? Or is there something more sinister at play?