Interested in gaining new writers for "Doctor Who", script editor Robert Holmes discussed ideas for the programme with Robert Banks Stewart. After their meeting in early 1974, Stewart devised a storyline for a six-part adventure called "The Secret of Loch Ness". Stewart felt that Scotland's legendary Loch Ness Monster would make an ideal basis for a story because there were so few details about the mythical creature. Although at first focusing on the Loch Ness Monster itself, Holmes encouraged Stewart to concentrate more on the Zygons, the shape-shifting aliens of the story. As the story evolved, it was known variously as "The Loch", "The Secret of the Loch", "The Loch Ness Monster", "The Zygons" and finally "Terror of the Zygons".