Ole Brindessen sees swindler Eddie Royce commit murder.

Smith and Romack investigate a series of bombings that rock Denver. The detectives can find no apparent connection between the two victims, one a mine owner, the other an Irish traveling salesman, until they discover a ball of twine in a popular boarding house that was linked to both crimes.

Enrico Spanato, a Sicilian interpreter is accused of killing a fellow Italian by several of the dead man's friends. Although Smith finds evidence that someone might have fired a shot at the interpreter, he can find no one who who will testify that the shooting was self-defense because the Italians in the neighborhood fear the growing power of the Mafia.

Whispering Smith captures Sam Chandler, a fugitive near the Mexican border. His plans to return him to Denver where he is wanted for murder are dashed when the two men are captured by Mexican bandits who only keep them alive to serve as personal slaves.

Smith and Romack have their hands full investigating a violent death that might be murder and dealing with a gang of ex-convicts who have suddenly descended on Denver. The former wards of the state appear to be planning to settle an old score, but who is the would-be victim? And is the gathering related to the late night shooting that Bob Mullet claims was self-defense?

Two outlaws steal a valuable jeweled statue from a Catholic church, but the parish priest refuses to give Smith a description of the villains unless he agrees to pursue them unarmed. The Denver detective reluctantly agrees and manages to catches up with the culprits in the desert. Smith begins a deadly game of cat-and-mouse in the middle of the waterless wasteland using canteens of water as deadly weapons.

A not-so-devoted husband hires a Kansas City killer to travel to Denver to murder his wife when the couple arrive by stagecoach several days later. After the young woman dies, he sets about arranging for his mother's return to England after an absence of 14 years. The older woman, however, becomes suspicious of her doting "son's" true identity.