People commit unthinkable acts every day. Time and again, we grapple to understand what drives a person to do such terrible things. But what if all of the questions we're asking are wrong? What if the cause of all evil is not a matter of what, but who? When three college friends stumble upon the horrific origins of the Bye Bye Man, they discover that there is only one way to avoid his curse: don't think it, don't say it. But once the Bye Bye Man gets inside your head, he takes control.