After an accident, the TARDIS lands on a luxury star-liner. Leaving their ship to repair itself, the Doctor, Leela and K9 find themselves facing a great terror: mingling at a cocktail party. Something seems awry behind the pleasantries, however. Guests are going missing, and equipment is breaking down. When the Doctor investigates further he discovers that the star-liner is literally on course for disaster. But no-one seems surprised by this information, still less troubled. What’s going on? And can the Doctor and his friends save everyone... when nobody wants to be saved?