The New Teacher

The Doctor meets an old friend, Sarah Jane Smith, and Rose Tyler discovers the legacy of being a Time Lord’s companion.

Led to Deffry Vale High School by Mickey, who's been following mysterious UFO sightings and some strange staff changes, The Doctor infiltrates the school as a new teacher while Rose is a dinner lady.

There they witness strange goings on especially with some very intelligent children and some very strange lessons. They soon discover that Mr. Finch, the headmaster has been changing the school to improve the students' performance - changes that include free lunches with special chips. The Doctor and Rose discover that alien Krillitanes, beings who have evolved by taking on the characteristics of other species, have taken over the school.

Rose Tyler

But there is someone else in the school – a journalist called Sarah Jane Smith who is also investigating the school. But a shock awaits her when she discovers the TARDIS in the school and so she finds herself reunited with The Doctor.

With the help of Sarah Jane and his current travelling companions The Doctor is able to uncover the reason for the Krillitanes presence at the school - they are brainwashing the children so that they can crack the Skasis Paradigm, the universal theory that controls the building blocks of the universe. With this power the Krillitanes will then be able to take full control over time and space.

Sarah Jane Smith

The Doctor also discovers that Sarah Jane has brought along K9. But K9 is no longer functioning. The Doctor though manages to fix K9 who, after analysing the cooking oil being used in the kitchen, tells The Doctor that it is what is being used to enhance the intelligence of the children – The Doctor also realises that the oil is harmful to the Krillitanes and so can be used to defeat them.

With the paradigm nearly solved Mr. Finch propositions The Doctor by tempting him with the ability to save the Time Lords and override human mortality. The Doctor though refuses – which angers Mr. Finch causing the Krillitanes to take revenge. As Mickey unplugs all the computers, allowing the children to flee, The Doctor leads the Krillitanes to the kitchen. Upon their arrival, K9 opens fire on the oil barrels, destroying the Krillitanes, the school, and himself.

As the TARDIS departs, leaving Sarah Jane behind to carry on with her life, she finds that not all is not lost as The Doctor has left behind a brand new K9 as a parting gift. Meanwhile aboard the TARDIS The Doctor has a new travelling companion as Mickey has requested to join him and Rose in the TARDIS.