The Sarah Jane Adventures: Revenge of the Slitheen - Part 1

It's Maria, Luke and Clyde's first day at their new school - and something's not quite right. The food keeps going off, there's a funny smell in the air and the new technology block is hiding some dark secrets. The friends soon make a shocking discovery: Evil alien race the Slitheen have disguised themselves as teachers as part of a deadly plan that threatens the future of the entire Earth.