by Dennis Spooner
After receiving a tip-off that someone is making a drop in Canada, Steed, Gambit and Purdey arrive at the site to find that the agent, Czibor, has been shot. His dying words are "Forward Base", but more puzzling is the fact that he is carrying an advanced missile guidance system. The package is left in the care of Purdey and Gambit, but when another agent, Halfhide, arrives, instead of making off with the package, he tosses it into the waters of Lake Ontario. Upon retrieving the system from the depths, Purdey finds is actually another older, obsolete model. Strange events take place on the shore of the lake: a local fisherman finds himself at sea one minute and ashore the next; and Purdey witnesses Halfhide jump fully-clothed into the water, only to later emerge in a dressing-gown. Investigating in a dinghy, Purdey is abducted by frogmen, and awakes inside Forward Base, an underwater missile base built by the Russians in preparation for World War III, which has been in the lake since 1969, when it sneaked in under cover of Typhoon Agatha. Steed goes fishing with a magnet, which enables him to find the entrance to the base; when he informs the crew that unless they surrender, they will be destroyed by an anti-sub flotilla, they emerge, held at gunpoint by Purdey.
Patrick Macnee (John Steed), Gareth Hunt (Mike Gambit), Joanna Lumley (Purdey), Jack Creley (Hosking), August Schellenberg (Bailey), Marilyn Lightstone (Ranoff), Nick Nichols (Malachey), David Calderisi (Halfhide), Maurice Good (Milroy), John Bethune (Doctor), Anthony Parr (Glover), Les Rubie (Harper), Toivo Pyyko (Clive) Ara Hovanessiaan (Czibor), Richard Moffatt (Radio Operator)
Directed by Don Thompson
Produced by Albert Fennell and Brian Clemens
LWT - 18th November 1977
*Featuring John Steed, Mike Gambit and Purdey
*Produced in Canada