 The Doctor(Sylvester McCoy) and Ace(Sophie Aldred) arrive on the earth colony of Terra Alpha. A colony that is under the misguided dictatorship of Helen A(Sheila Hancock). On Terra Alpha, sadness and misery are a capital crime and anyone who does not adhere to these strict laws are executed on the spot by Helen A s secret police. A motley crew of female assassins who are known only as  The Happiness Patrol.  The Doctor and Ace make it their mission to put a stop to Helen A s narrow minded and harsh regime. But that is all easier said than done. What with  The Happiness Patrol , undercover snoop Silas P(Jonathan Burn) and Helen A s carnivorous little pet Fifi to contend with. They could do with all the help they could get. Joining forces with Earl Sigma(Richard D. Sharp), rogue Happiness Patrol member Susan Q(Lesley Dunlop)and the native inhabitants of Terra Alpha who were driven in to the pipes and sewers of the colony. The Doctor and Ace s revolution gets well under way. But there is one threat that the Doctor hadn t banked on. Helen A s prized chief executioner. A crazed android and creator of confectionery that is lethal. The robotic menace known only as the Kandy Man.