Doctor Who 17x25

The Shadow, now with control of K-9, awaits the arrival of the Doctor and company in the cave where he took control of the princess. Meanwhile, Princess Astra joins Romana and the Doctor in the TARDIS, where he had locked the Marshal in a continual time loop just before attacking Astrios. Returning to the cave where Princess Astra was held captive, K-9 pursues the Doctor, while Astra captures Romana.