School Reunion is the third episode of Series 2. It featured the return of Liz Sladen as Sarah Jane Smith to the TV show, at the cost of her Big Finish solo series being cut short because Rusty was a cunt who wouldn't allow Briggs to use any characters that appeared in NuWho, even if they were originally classic in origin. He'd do this again with Davros later on, but I digress.
Anthony Head tries to take over the universe using schoolchildren who he forces to become super-intelligent by eating lots of chips.
Rose and Sarah Jane fight over the Doctor. Mickey has a good laugh at his expense.
The plot is shit and there are some dumb scenes, but seeing Sarah Jane again was pretty cool. And K-9 shows up again as well, looking disco.