When Townsend Loving is the victim of a fatal hit-and-run accident, the Bead Weekly needs a new Editor-in-Chief. His widow, Della, begs Townsend's boyhood friend, Jeet Vaughn, to take care of the paper for a few months while she gets things squared away. So the whole family (Robin, Jeet and two horses) packs up and heads to Bead, Texas to search for a short-term rental and a green pasture.

The Robin Vaughn stories are usually horse-books. Robin is a horsewoman. She is involved with her horses, and the normally appearing in these book would not exist without the horses. Death on the Diagonal only peripherally concerns horses. Plum and Spier make their appearances, but then go on grazing while Robin tries to figure out what the problem (non-horse related) is in Bead. There is a horse-related subplot but it feels like it was written separately from the rest of the novel and then not fully integrated.

There are several awkwardly tangled threads that get straightened out and tied up by the end. Why did the sheriff close the case on the hit and run? Why is Anthony Perkins hanging out in Bead? Who is scheduled to be the sacrifice to the goddess Kehmbe? As you may have guessed, it was very nearly Robin!