The most dangerous double agent ever to plague the British Intelligence field is operating and it looks to John Steed as though it is Mother. But then Emma Peel and Cathy Gale don't agree, Dr. Keel is believing an ape is to blame, and Tara King is just confused. All the major Avengers from the original series return to work together in this extremely well-crafted novel that is a success not only as a story but also as a welcome reunion of some old friends.