The Doctor and his companions learn that a group of Daleks, equipped with a time machine of their own, are on their trail with orders to exterminate them. The Doctor et al flee in the TARDIS and a chase begins! First stop is the planet Aridius and they then go onto various other places including New York's Empire State Building, the ship Mary Celeste and a haunted house! Eventually both time machines arrive on the planet Mechanus, where the Daleks try to kill the Doctor's group using a robot double of him. The travellers are taken prisoner by the Mechanoids - a group of colonizing robots - and meet Steven Taylor, a stranded astronaut who has been the Mechanoids' captive for the past two years. The Daleks and the Mechanoids do battle, leading to their mutual destruction, whilst the Doctor and his companions escape with Ian and Barbara returning home to Earth in the Dalek's time machine!
Aired: 5 Jun 1965