The Doctor and Vicki are surprised to discover a stow-away aboard the TARDIS and welcome Steven Taylor, who survived the destruction of the Mechonoid city, aboard.
Using a Time/Space Visualiser taken from the Moroks’ space museum, the Doctor, Barbara, Ian and Vicki discover the Daleks have built a space/time vehicle and are in pursuit.
When the TARDIS jumps a time track and lands on the planet Xeros, the travellers are given a glimpse of their own future in which they are fated to become exhibits in a museum.
The TARDIS lands in Palestine where King Richard the Lionheart wages war with Saracen ruler Saladin. At King Richard’s court Ian is knighted and permitted to search for Barbara.
The TARDIS is dragged down to the planet Vortis where the travellers discover an alien being known as the Animus has taken over the planet, enslaving the antlike Zarbi as soldiers.
The year is 64 AD and the Doctor and his friends take a holiday staying in a villa near Rome, but Barbara is sold as a slave and Ian is forced to fight in the arena as a gladiator.
The TARDIS takes the travellers to the planet Dido.
When they land in London, Ian and Barbara are happy to be home but celebrations are cut short on realising they’re in the 22nd Century and Earth has been conquered by the Daleks.