The Chronicles of Chiswick

The TARDIS strands Eleven at Clara's — six years later than he meant to arrive. Trapped across his timeline and up to his delicate eyebrows in spoilers, he receives a cryptic message from Twelve: one of his former companions is in danger, and he'll need the help of the others to save her. It's a reunion the Doctor would love to remember... but the laws of time doom him to forget.