He was well-known for producing cheap food from the sea. He went missing, and was reported as dead, but in reality he had found the submerged city of Atlantis and was living there. When the Second Doctor and his companions were about to be sacrificed to the Atlantean goddess Amdo, the Doctor sent a note to Zaroff. Damon gave Zaroff the note and he became intrigued and put a halt to the sacrifice. He put Ben, Polly and Jamie to work in the mines and took the Doctor to his laboratory. When the Doctor sabotaged the power system to rescue Polly from an operation, Zaroff became suspicious of him and wanted to keep him close.