On Maria's and Luke's first day of school, something is wrong. The food is off, the place smells strange, and some of the teachers are acting suspiciously. With the help of Sarah Jane and their new friend Clyde, they uncover an unearthly plot which is culminating in their school's new technology block...

Bringt uns die Slitheen aus der ersten Who-Staffel wieder - ob die alle Materietransmitter hatten wie die gute Margaret?