Next Time: The Sarah Jane Adventures: Sky

Alien investigator Sarah Jane Smith is back on CBBC with a fifth and final series of the award-winning The Sarah Jane Adventures, starring the late Elisabeth Sladen.

Created by Russell T Davies, the hugely successful Doctor Who spin-off returns for a brand-new, six-part series, featuring three stories, each told over two episodes. The first is the spectacular two-part story, Sky.

In today's episode, Sarah Jane finds a baby girl on her doorstep and tries to find out who abandoned her.

At a nearby nuclear power station, a beautiful woman appears out of thin air and uses alien powers to take control. She's looking for something – and realises that Sarah Jane may just have it...

Today, Sky has undergone an amazing transformation, but in doing so has triggered a countdown that no one can stop.

As Sarah Jane and Sky find themselves trapped between the alien war fought by Metalkind and Fleshkind, Clyde and Rani face a race against time to stop the biggest bang in history...