Season 4, Episode 4 - "The Sontaran Stratagem"
26 April, 2008
The Doctor is called back to modern-day Earth by an old friend as an old enemy starts some new troubles. Aided by the Rattigan Academy, the Sontarans establish a covert base at the mysterious ATMOS Factory. The Doctor must stop the Sontarans from unleashing a potent terror that will bring the world to its knees.
