The Master wants to plunder one of the most secure vaults in the universe, the Repository. He's got a plan, and a deadly new weapon to assist him. However, as the Master quickly discovers, getting in might be easy, but getting away with it might cost him everything.
According to one account, the Master had the appearance of Roger Delgado while on Gallifrey. According to another, he had Anthony Ainley's likeness. According to another one, the one with James Dreyfus's appearance was his original incarnation.
While fighting to extend his life at the end of his regeneration cycle, many bodies were possessed by the Beevers incarnation but all kept somehow reverting to his real being until he finally regenerated into the MacQueen one. Hence, these sections cannot be strictly chronological