Kai (Leehom Wang) awakens one morning on his Shanghai houseboat--alone. His girlfriend Emma (Olivia Munn) has mysteriously vanished, and all he has to go on is her phone. Deeply disturbed, Kai uses the phone 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? As he pieces together the harrowing truth, there are parts of both Emma's life and his own that leave him with some difficult questions, and some unsettling answers.