The Sea Devils take over the naval base and the Doctor is forced to help the Master find a way to revive their colony.
Quest roles:
Edwin Richfield(Mestor), Pat Gorman(Pilot), Roger Delgado(The Master), Peter Forbes-Robertson(Chief Sea Devil), Martin Boddey(Walker), John Caesar(R/T Soldier), Alec Wallis(Warner), June Murphy(3rd Officer Jane Blythe)