The Devil's Drum — William Colt MacDonald

One stormy night in Devil's Drum country, Texas, a freight train is halted by a landslide. Two teamsters with fake orders from one of the railroad's top officials ride up, requesting twenty cases of preserves from the startled crew - but are waylaid and murdered on their way into town. So begins one of the most mystifying jobs that detective Gregory Quist has ever taken on; and murder is committed again before he learns what was in the cans innocently labelled as strawberry jam. In the course of his investigations, he is helped and hindered in turns by the local authorities, the neighboring ranchers, a Texas Ranger of deadly purpose, and two baffling young women. But it's the proprietor of a small cantina across the Rio Grande in Mexico who aids Quist in bringing the perplexing case to a violent conclusion.