Classic Who S11 • Serial 1 · (4 episodes)
The Time Warrior
When scientists start to go missing in the 20th century, the Doctor is called in by the Brigadier to investigate. His investigations lead him to deduce that they are being kidnapped through time, and he sets off in pursuit, unknowingly kidnapping journalist Sarah Jane Smith in the process.
Arriving in the middle ages, the Doctor and Sarah find themselves caught up in the machinations of the robber baron Irongron and his "star warrior". The alien, a Sontaran named Linx, is arming him with modern weapons in return for helping him repair his damaged ship, and it's up to the Doctor and Sarah to stop him from ruining the Earth's timeline.
4 Episodes:
England, the 12th century. Robber baron Irongron is recruited by Linx, a Sontaran warrior whose starship has been forced down on Earth. Linx is forced to use a time-travel device to steal resources and scientists from the future to repair his ship, but in doing so involves UNIT and the Doctor...
The Doctor tracks the missing scientists to Irongron's castle, where Linx is using them to repair his spaceship and construct advanced weapons for Irongron.
The Doctor escapes the castle with Sarah and Hal and must persuade Sir Edward to trust him before Irongron launches an attack on them.
The Doctor attempts to return the scientists to their own time, before Linx tries to use his spaceship and destroys the entire castle.