Angered by a noisy motor bike gang who ride on their land, elderly sisters Cynthia and Ermyntrude Peck, who claim to be witches, cast a spell which causes all the motor-bikes to stall. Not only that but almost every electronic and mechanical object in the area also tends to malfunction. Mrs. Gale in her leathers joins the gang to ask permission from the sisters to ride on their property and in the process discovers that these two sweet old dears may actually be in possession of a sophisticated long range jamming device. They may have built a better mouse-trap but it will cause some unsavoury types to beat a path to their door.

Also on The Avengers: Season 3, disk 3

Five years earlier the British Secret Service ordered Mark Charter to assassinate Sharp, a renegade British agent who defected to the enemy state of Abarain. But now the two countries are at peace and it is Sharp who has come to broker an important arms deal in Britain on behalf of his government. Charter, supposedly dead but actually in jail, is now free and is coming after Sharp, giving Steed the unusual task of protecting an erstwhile traitor.

Also on The Avengers: Season 3, disk 6

Agent Vinkel is the latest spy from 'the other side' to get polished off and, as ever, Steed is implicated but he persuades the opposition it would be best for the two camps to team up and expose a third party, committing the murders for their own agenda. Mrs. Gale is paired with Russian Martin, who, alas, gets killed at the dentist's. Steed and his partner, Kim Lawrence - actually an actress employed by the other side to test him - follow a trail to a charm school for English gentlemen - in reality an academy for assassins.

Also on The Avengers: Season 3, disk 7