With the Doctor and Jo being held prisoner, the Master convinces Mailer to help him steal the Thunderbolt.
Quest roles:
Richard Franklin(Mike Yates), Nicholas Courtney(Brig. Lethbridge-Stewart), Terry Walsh(Guard (uncredited)), John Levene(RSM Benton), Dave Carter(Grierson), Roger Delgado(The Master), Michael Sheard(Laurence Scarman), Martin Gordon(Prison Officer), William Marlowe(Lester), David Calderisi(Charlie), Cy Town(Dalek Operator), Bill Matthews(Prison Officer), Hayden Jones(Lenny Vosper), Fernanda Marlowe(Corporal Bell), Barry Wade(Prison Officer)