The Doctor, with Polly, Ben and Jamie in tow, lands the TARDIS on a volcanic island where they are captured and taken into a cave complex. It soon becomes clear that this tiny island is all that remains of the ancient Atlantean civilisation. Mad scientist Professor Zaroff (played with a Large Ham by Joseph Furst) has convinced the Atlanteans that he can raise the city from the sea, but in reality he plans to drain the ocean into the Earth's core and thereby destroy the planet. Just because, OK? For a long time it was thought that only episode 3 remained, until episode 2 turned up in 2011.