After a brawl in Tampico, Mexico, Costigan is approached by a group of cowboys from the Diamond J ranch, who are in search of a strong fighter to take on a formidable opponent from a nearby mining company. Despite initial reluctance, Costigan is drugged and taken to the ranch, where he agrees to fight after a series of misadventures and a demonstration of his unwillingness to be coerced.

The central event is Costigan's bout with Snoots (Biff) Leary, an old acquaintance from Galveston, now working for the mining company. The fight is intense, evenly matched, and interrupted by an attack on the mine by the bandit Lopez the Terrible and his gang. The subplot of Lopez's attempt to kidnap Joan, the ranch owner's daughter, adds a layer of drama and showcases Costigan's and Leary's heroism beyond the ring.

The story concludes with Costigan and Leary, despite being wounded, deciding to finish their fight, underscoring their competitive spirit and mutual respect. The tale is punctuated with humor, the themes of loyalty, and the valor of standing up for friends and what's right.