School Reunion (Doctor Who) - Plot

Plot

The episode opens with Mr. Finch, the headmaster of Deffry Vale School, meeting a student outside his office. She tells him that she's an orphan, and he escorts her in and transforms into a winged creature that consumes her. The Doctor is shown working as a substitute teacher at the school, and during a class he meets a boy with knowledge far beyond normal. During lunch the Doctor speaks briefly with Rose, who is working as a lunch lady. Rose and the Doctor note that the school is unusually well behaved, and everyone seems to eat a large amount of the cafeteria's chips. Rose is unhappy with her job, but the Doctor notes that it was Mickey who encouraged them to investigate the school. During service, Rose notices that the other kitchen staff have to wear hazmat suits to handle the chip oil, and one lady that is splashed with it gets horrible burns.

Later on, Mr. Finch introduces the other teachers to Sarah Jane Smith, whom he believes is a reporter doing a cover story on the school. Upon seeing Sarah Jane the Doctor is delighted, and he quickly introduces himself as John Smith. That night, after the school is locked up, the Doctor along with Rose and Mickey break in to investigate further. At the same time, Sarah Jane is also snooping around the school and is shocked to open a door and see the TARDIS. She quickly exits the room and encounters the Doctor, who reveals that he's regenerated six times since he last saw her. They regroup with Mickey and Rose, and Rose quickly begins competing with Sarah Jane for the Doctor's attention. In Mr. Finch's office they discover 13 giant bat creatures sleeping on the ceiling and decide to leave the school. They head to a local diner, where Sarah Jane gives the Doctor her broken K-9 Mark III. The Doctor repairs him and uses his sensors to determine that the chip oil is actually Krillitane oil.

The next day, the Doctor confronts Mr. Finch. He confirms that he and the others are Krillitanes and reveals his plan to use the students in the school to solve the Skasis Paradigm. Doing so will give Finch complete control over reality, which he offers to the Doctor in exchange for the Doctor's help. The Doctor refuses, despite the knowledge that he could restore the Time Lords if he helps Finch. Sarah Jane and Rose break into the school's computers whilst Mickey and K-9 wait in the car. Mickey is alerted by Kenny, the only student who wasn't eating the chips, that the other students are in trouble. They use Sarah Jane's car to crash through the school's doors and unplug the computers, allowing the children to flee. The Doctor leads the Krillitanes to the kitchen, where K-9 is waiting to detonate the chip oil drums. K-9 buys the Doctor time to escape before blowing up the drums, spraying the Krillitanes with oil. They explode and burn, detroying the school. The Doctor consoles Sarah Jane over the loss of K-9.

The Doctor returns with Rose, Mickey, and Sarah Jane to the TARDIS. Sarah Jane declines a second chance at travelling in the TARDIS, but encourages Mickey to go. Sarah Jane tells Rose to travel with the Doctor as long as she can, and offers to help her if she ever needs it. A teary-eyed Sarah Jane says goodbye to the Doctor and watches as the TARDIS dematerializes, leaving behind a new K-9 unit for her.