Robert Conrad gives a coldly effective performance as Milo Janus, an owner of a chain of health spas who is conning the franchisees by getting them to purchase over-priced items from companies he actually owns. When one franchisee latches onto Janus's scheme and threatens to expose him, Janus murders him...
The script gets a little immersed in various secondary characters around the half-way mark and the episode could easily have been condensed. Nevertheless, the murder/made-to-look-like an accident scenario is excellent, the increasingly bitter relationship between Columbo and Janus (the hospital scene where Columbo chastises Janus is unique) is well-portrayed and there is some really good conversational waffle from Columbo.
The ending has provoked much debate for years; for me the actual reasoning is fine, but the script-writer stretches credibility in the way it is triggered in Columbo's mind.