A late-night knock at the door should be easy to ignore—until it starts happening every night at exactly 2:17 AM.

At first, it’s just a sound. Then a shadow. Then something far worse.

As reality begins to slip, one man discovers that whatever is knocking isn’t outside his door… it’s trying to get in from somewhere much closer.

And when the third knock comes, there may be no way to stop what’s already inside.