The Diner

Nephilim; The offspring of an angel and a human. Highly dangerous and wanted by all of Heaven immediately after conception.

The Winchesters; Heaven and Hell's worst nightmare. Highly dangerous. If spotted, run and hide. Don't interact.

What happens when, on the way back from a hunt, the Winchesters run into the one thing that could destroy the world and it's taken the form of a thirteen year old girl?