Parts: 1 (45-minute)
Writer: Toby Whithouse
Airdate: 29 April 2006
Production Code: n/a

Doctor: tenth
Companions: Rose, Mickey, Sarah, K-9 mark three

Ceature Feature: Krillitanes

Story: Alerted by rumors of unusual UFO activity, Mickey asks the Doctor and Rose to return to Earth and investigate a local high school where strange activities may be afoot. The Doctor and Rose successfully infiltrate the school - he as a teacher, she as a lunch lady - but things seem to be relatively normal. Maybe even better than normal; this particular school has recently been taken over by a forward-thinking headmaster whose comprehensive policy changes and staff substitutions have dramatically affected the students' productivity. But slowly, the Doctor and Rose begin to perceive oddities: the students are all unusually well-behaved, some of them possess knowledge that isn't even known on Earth, and the kitchen staff are doing something suspiciously secretive.

As it turns out, Mickey isn't the only person to smell a rat at Deffry Vale School - there's also journalist Sarah Jane Smith, who suspects something strange is happening at the school and decides to carry out a bit of investigation herself. Before long, Sarah unknowingly meets the newly-regenerated Doctor... but their reunion may be short-lived, for something evil is stirring in the school hallways after dark, and it likes the taste of human flesh.