Across an action-packed twenty-six episodes, the Doctor and Jo (Katy Manning) face off against Daleks, Ogrons, Sea Devils, Ice Warriors, Mutants and their old enemy the Master (Roger Delgado). Joining them in their adventures are the UNIT team of Brigadier Lethbridge-Stewart (Nicholas Courtney), Captain Yates (Richard Franklin) and Sergeant Benton (John Levene).