A knock from Afar

Some doors should never be opened.
On a freezing January afternoon, Eric and his best friend Billy are playing soccer when a mysterious old man approaches them.
He calls himself Uncle Phil.
When Billy follows him inside a strange house, Eric realizes something is terribly wrong. A scream comes from behind the door, followed by three words written across a frosted window:
YOU ARE NEXT.
Eric runs home and tells his father everything. The police arrive-but when they confront Uncle Phil, there is no evidence. No blood. No missing boy. Nothing.
Even worse, everyone who enters the house seems to come back different.
Now Eric is the only person who knows the truth.
But if nobody believes him...
Who will save him when Uncle Phil comes knocking?