Maelstrom

The Doctor, Mel and Hebe visit the archipelago world of Veludia, only to discover a planet beset by electromagnetic storms where three survivors traverse the seas in a ramshackle township. These survivors are 'corps' - bodies used as hosts for minds stored in the vessel’s ‘mind-drive’ - and the Doctor, Mel and Hebe are seen as welcome replacements. But there's something lurking in the waters below, something of rage and power that wishes to destroy them all: the Maelstrom!