The fourth season of The Avengers was the first season to be telecast in the United States, the first to be filmed rather than videotaped -- and, most importantly, the first to feature Diana Rigg. When series co-star Honor Blackman decided to leave the series at the end of the third season to revitalize her film career (which she did, spectacularly, as Pussy Galore in Goldfinger), the search began for an attractive and athletic actress who could successfully fill Blackmans boots as the very resourceful, very sexy partner of bowler-hatted British secret agent John Steed (Patrick Macnee). Like Blackmans character, Cathy Gale, the new Avenger girl, Emma Peel, is a talented amateur whose sang-froid in the face of danger, to say nothing of her outstanding martial-arts skills, come in quite handy whenever Steed -- and by extension the British government -- needs a good operative to smash an enemy spy ring or stop a maniacal master criminal in his tracks. The producers first choice to play the leather-clad Mrs. Peel (Mrs. because her husband has been missing and presumed dead for several years) was actress Elizabeth Shepherd; however, after appearing in one test episode, The Town of No Return, Shepherd was deemed competent but unsuitable, and Diana Rigg was brought in to appear in the refilmed version of the above-mentioned episode. As it turned out, Rigg was perfect for the role, and she would remain as Mrs. Peel for the next three seasons.

Unlike Honor Blackmans subtly sensuous and down-to-earth Cathy Gale, Diana Riggs Emma Peel is charmingly aristocratic and aloof. Also, in contrast with the implied intimate after-hours relationship between Cathy and Steed, it is abundantly clear that Mrs. Peel keeps Mr. Steed safely at arms length -- though the twinkle in her eye, and that inimitable sly smile, suggests that she might not be entirely averse to a fling with her partner should the opportunity arise! Even so, Cathy Gale and Emma Peel have a lot in common, including a predilection for getting trapped in campily perilous predicaments: indeed, in her second Avengers episode, The Gravediggers, Mrs. Peel is snugly tied to a railroad track as a deadly model train bears down on her and a tinkling silent-movie-style piano is heard in the background! Although not the first episode in which Diana Rigg appears, the first Avengers to be seen on American TV was the legendary The Cybernauts, an outlandish sci-fi outing which perfectly exemplifies how far the series had come from its earlier realistic episodes. Of the remaining fourth-season installments, five were removed from the original American network run because they were deemed too provocative. These include A Surfeit of H20, Silent Dust, The Quick-Quick Slow Death, A Touch of Brimstone, and Honey for the Prince -- the latter offering the spectacle of Diana Rigg in a belly-dancer outfit, replete with a jewel in her navel. ~ Hal Erickson, All Movie Guide