This is the last episode on the new Season 4 box set, but fortunately not the last original episode aired by CBS.
There is no Arte, no partner, other than a "put-on-the-spot" by the chairwoman of the board - Lionel, a young man trying to prove himself.
Board members are being murdered, and the new chairman (a woman) casts the only descenting vote in not allowing West to protect them.
Checking stock sales record, Lionel stumbles onto the address used by buyers involved in a gimmick to dump shares, causing the price to fall, and then buying them back at fire sale prices.
West comes to the rescue.
This is a very sexist episode (during the show, and especially the tag), lacks any real excitement, and was rightly NOT selected as the last episode to air.
There are no major guest stars known to me, and it is rather a lame episode. Not one I will likely watch again. I've got too many box sets, and too many other enjoyable West episodes to watch again and again.
There is a pretty song performed by Kyra (assistant to the woman chairman), set to the tune of Greensleeves, which West watches from a balcony he has just ascended to using his derringer to propel a device that lifted him to that height. Likely edited out of syndicated versions as it is lenthy, and doesn't add anything to the episode.