Doctor Who — The Sontaran Stratagem

In BBC One's Doctor Who tonight, Martha Jones summons the Doctor back to modern-day Earth, but an old enemy lies in wait.

With the mysterious ATMOS devices spreading across the world, Donna discovers that even her own family is not safe from the alien threat — but is it too late to save them?

David Tennant plays the Doctor and Catherine Tate plays his new companion Donna Noble.

Freema Agyeman plays Martha and Christopher Ryan also guest stars.

Doctor Who: The Sontaran Stratagem (series 4, episode 4/13), BBC One, Saturday 26 April 2008, 6.20pm.