Release Message:  The fiendish Slitheen have been unmasked as the ones who crashed the spaceship into London as part of a ruse to trigger World War Three. Featuring Annette Badland as Margaret Blaine.

Description:  The fiendish Slitheen have been unmasked as the ones who crashed the spaceship into London as part of a ruse to trigger World War Three. But how can The Doctor save the planet when he's trapped inside a locked room?