The human colony of Terra Alpha is a contradiction to the outside observer. A world said to be full of sound and colour but overshadowed by an air of opression and fear of upsetting the status quo.This week, Paddy and Tricia follow The Doctor and Ace as they investigate the mysterious happenings goings on at Terra Alpha and soon find themselves at the mercy of a system where lack of enthusiasm could be deadly. Can they discover the sinister secret of the colony whilst not running afoul of The Happiness Patrol?