"Frontios buries its own dead", or so the saying goes. The Doctor, Turlough and Tegan are forced into landing on the remote planet of Frontios, a human colony where deaths go unaccounted for. What lies beneath the surface, dragging its victims down?

Belfast. Four men meet -'for a drink', says Denis. The car is ready in the back alley. The youngest, Terry, isn't drinking. He's begun to have doubts about his new company - and they about him.