On the planet Vortis, the Doctor and his companions aid the butterfly-like Menoptra in their battle against the parasitic Animus and its mind-controlled minions, the ant-like Zarbi.

The adventures of The Doctor, a time-traveling humanoid alien known as a Time Lord. He explores the universe in his TARDIS, a sentient time-traveling spaceship. Its exterior appears as a blue British police box, which was a common sight in Britain in 1963 when the series first aired. Along with a succession of companions, The Doctor faces a variety of foes while working to save civilizations, help ordinary people, and right many wrongs.