Simon (Jason Bateman) and Robyn (Rebecca Hall) are a young married couple whose life is going just as planned until a chance encounter with an acquaintance from Simon's high school sends their world into a harrowing tailspin. Simon doesn't recognize Gordo (Joel Edgerton) at first, but after a seemingly coincidental series of encounters proves troubling, a horrifying secret from their past is uncovered after nearly 20 years. As Robyn learns the unsettling truth about what happened between Simon and Gordo, she starts to question: how well do we really know the people closest to us, and are past bygones ever really bygones?
When married couple Simon (Jason Bateman) and Robyn (Rebecca Hall) unexpectedly encounter Gordo (Joel Edgerton), an acquaintance from Simon's past, little do they know that their perfect lives will be thrown into a terrifying tailspin. At first, Simon doesn't recognize Gordo, but after a troubling series of uninvited encounters and mysterious gifts, a horrifying secret emerges. As Robyn learns what really happened between Simon and Gordo, she begins to question how well she knows her spouse.