Stefan Veliko, a young Russian pianist, is making his concert debut in London. However, he is being used as a pawn in a game to wreck Anglo-Soviet relationships. First a young woman is found dead in his apartment, which is exploited to blackmail him into killing a delegate during a piano recital. Fortunately, he has the Avengers on his side, although it is a close call for Mrs. Gale.

Also on The Avengers: Season 3, disk 1

Young Highland Guardsman Corporal Craig is found shot, his corpse containing bullets from three separate guns. He has been shot by a firing squad, for treason, and when Steed re-enlists in the Army under his old rank of Major, he could very well end up the same way, thanks to a bizarre plot by latter day Jacobites, whose plan is to overthrow the monarchy and crown a descendant of the Stuart dynasty, a descendant who just happens to be Mrs. Gale!

Also on The Avengers: Season 3, disk 7

In investigating the death of a colleague who has died in a fire Steed and Mrs. Gale find an ornately-carved chess piece in the dead man's possession. This leads them to an importation business. On the face of it the commodity is lobsters but it is the front for a gang trying to smuggle heroin into the country.

Also on The Avengers: Season 3, disk 7