At the Iceworld Space Trading Colony on Svartos, the Doctor and Mel unexpectedly encounter an old 'friend.' The penniless and desperate Sabalom Glitz has only one option to leave Svartos: find the fabled 'Dragonfire' treasure concealed somewhere in the depths of the planet. Joined by Ace, a teenage waitress with a love for explosives, the group ventures off to uncover lost riches, not knowing that Kane, Iceworld's ruthlessly intimidating overlord, will gladly murder them all to gain possession of the Dragonfire himself. Before long the Doctor finds himself playing a deadly game of cat and mouse with Kane's mercenaries, descending through the ice caverns ever closer towards the deadly gaze of the monstrous dragon that lurks below.