When 400-year-old tribal mummies inexplicably return to life and begin murdering tourists on an exotic alien island, the Doctor's initial urge to investigate lands himself, Jamie and Victoria right in the middle of a jungle holocaust. Ferocious cannibals and deadly beasts stalk the swamps, mummies lurk amongst the trees and the peaceful, civilised locals are reverting to long-forgotten head-hunting practices. Something is giving a clarion call to savagery, something that can only be found in the deepest darkness at the heart of the hostile rainforest. It could well be the end of the river for the TARDIS companions as they find themselves involved in a horrific jungle conflict between desperate guerrilla tribesmen and merciless colonial forces. Cannibalism could be the least of their worries as evil stirs the pot and the dead reach for the living...