Set in the modern age, the tenth Doctor (David Tennant) and Martha, played by Freema Agyeman, attend the latest experiment by the acclaimed Professor Lazarus (Mark Gatiss), who successfully reverses his own ageing process. Entering his machine as an elderly man, the professor steps out with his body rejuvenated and youthful, but the transformation doesn’t stop there. Soon after, Lazarus morphs into a hideous creature that drains its victims of their life energy, and only the Doctor and Martha can stop him!

 First Broadcast: BBC One, 5^th May 2007

Written by: Stephen Greenhorn

Directed by: Richard Clark