A pattern that I've noticed in season 4 are the episodes dedicated to just one of the Angels. It's starting to become a weakness, because one of the strengths of the show was the three Angels working together to solve a crime. This one features Cheryl Ladd, and her Kris is the lure used on a jewel thief who's jumped bail to Phoenix.
A really interesting note is that the jewel thief is played by Jonathan Goldsmith. He plays Vic Devlin as an amoral sociopath and pulls off the characterization with ease. What makes it fascinating all these years later is that Goldsmith is best known as the world's most interesting man in the dos Equis beer commercials. I would never have guessed that the guy who played Rick Devlin in Charlie's Angels in 1980 was the same man who became famous from the dos Equis beer commercials. He looks nothing like his younger self, although to be fair he started filming the commercials more than 35 years after the CA role.
The title is a bit misleading, mainly because Kris is only missing in the last 10 minutes of the episode. It's not the crux of the plot at all, Bosley and the others know that she's gone off to Phoenix to try and bring Devlin back.
The only other casting note is that Warren Berlinger makes his second Charlie's Angels appearance. Here he plays the morally ambiguous Fred Beck, a friend of Rick Devlin's. Berlinger had previously been in first season's Dirty Business, playing the director of dirty movies.
This is not a bad episode, but it's missing a little spark. In some ways I could see why the ratings for Charlie's Angels may have dipped in season 4, as they've drifted away from the original formula. And they've also tried to create more hard-hitting plots, rather than the glam and fun approach that they originally took in season 1 and successive seasons.