Adam, formerly known as Nigel Castle, was a British novelist. He was one of the people Sir Charles Grover brought together colonise New Earth. Adam agreed to the scheme and was appointed as an Elder aboard the spacecraft. However, he, and the others, had been duped. They were in fact inside a bunker beneath London.
Sarah Jane Smith was brought aboard the ship and initially believed, as they did, that they were in space. However, she soon protested, so Adam and Ruth, another Elder, subjected her to a period in the reminder room.
Adam contacted Grover, who he believed was on another spacecraft, asking him to visit and clarify the matter. He did so and talked with Sarah Jane and Mark about the lies he had told. Adam overheard this conversation and freed the pair. Sarah Jane convinced the other would-be colonists that they were lied to by opening the airlock. Once out of the spacecraft, they confronted Grover and the scientist Whitaker who accidentally sent themselves into the past. (TV: Invasion of the Dinosaurs)