AllMovie

Filmed during the production break between the sixth and seventh season of The Avengers, this episode served as the swan song for Emma Peel (Diana Rigg). . .and as an introduction to novice secret agent Tara King (Linda Thorson) (Though, technically, it was not the first episode in which she appeared). On this occasion, Tara assists Steed and Emma as they try to flush out a traitor in their midst. The episode's "gimmick" is a drug which induces amnesia -- and also a loose tongue. The final scene, in which Emma turns over the reins to Tara, is a classic. According to some sources, "The Forget-Me-Knot," written by Brian Clemens, was first shown in England on September 25, 1968, while other sources list January 12, 1969, as its first airdate. Be that as it may, the episode actually debuted on American television on March 20, 1968.