Air: Jan 14 1967. 4 eps, ep 2 and 3 found.
The Tardis lands on a deserted isle but they soon get captured and brought deep underground to an ancient thriving civilization. With them is a famed scientist, Professor Zaroff. He explains that they are in none other than the lost city of Atlantis and he has promised them to raise it back to the surface. But what The Doctor discovers is that his true plan is to destroy the whole world by blowing it apart with steam. He’s a MAD scientist actually. So it’s up to the Tardis crew to put this nutty professor out to pasture.