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.

Cast:William Hartnell, Jacqueline Hill, William Russell, Maureen O'Brien, Catherine Fleming, Roslyn de Winter,

Genre:Science Fiction, Drama, Adventure,

country:United Kingdom,

Production:BBC,