Since I work on the "Department S" guide I can be accused of having an automatic bias toward Peter Wyngarde. That is not the reason I rave about his performance in this episode of "The Champions". If anything, I see Wyngarde's Jason King character in "Department S" more as comic relief than central to the series. Wyngarde, to me, is much better at playing villains. Note, for instance, his performance as the leader of the Hellfire Club in the "A Touch of Brimstone" episode of "The Avengers" (which usually gets more notice because of Diana Rigg's "Queen of All Sin" outfit -- the reason it was banned from airing in the U.S. in the 60s).
In "The Invisible Man" Wyngarde plays a surgeon who has devised a plan to steal $30 million worth of gold. He gives a patient of his -- the administrator of the London gold depository bank -- an "invisible man" to torment the man into allowing the undetected theft of the gold. The gold is then melted down, poured into the mold for a press, and prepared for export to Sweden. Wyngarde's performance is flawless.
Lest this appear to be a post for the Peter Wyngarde fan club, I hasten to point out that the entire cast had an excellent script with which to work. The plot is superb, with the secret behind "the invisible man" only revealed near the end of the show.
One of the central, recurring themes of the series -- one of "the champions" becomes aware of danger that another is in (thanks to the gifts they received from the lost people in Tibet who saved them when their plane crashed) and has to convince the very skeptical Tremayne -- plays out here. Sharron suddenly stops listening to Tremayne when she senses Craig passing out from being locked in a gas-filled operating room and blurts out, "Craig's in trouble!" Tremayne always has the same expression of bewilderment and disbelief, but it never fails to amuse (especially since the audience is in on the secret that is kept from him).
It is hard to pick a favorite episode of "The Champions", since (with the exception of "The Interrogation", which was spliced together from clips of other episodes with a poor, flawed storyline) most of the episodes have suspenseful, well-written scripts and the chemistry between the three characters is evident. "The Invisible Man" is certainly one of the best episodes.
This episode is available on DVD in the U.S. through A&E Home Video.