Attack of the Graske

What is the red button episode?

From 8pm on Christmas night, Digital Satellite and Freeview viewers can truly immerse themselves in the world of Doctor Who.

Attack of the Graske is a mini episode of Dr Who with a twist - it allows viewers to become the Doctor's companion.

Viewers will get the chance to track down an evil alien life form by flying the TARDIS and completing a series of challenges set by the Doctor himself.

The challenge will be available throughout the night and after the January 1 repeat of The Christmas Invasion on BBC Three.