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?

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

Read our review of The Sontaran Stratagem.