In an unnamed Latin American country that closely resembles Mexico, the government fights a rural insurgency with torture, assault, rape, and murder. Soldiers descend on a town, cutting off the rebels from their cache of ammunition hidden in a field. A family of grandfather, son, and grandson are among the rebels in the hills. The grandfather, with his violin over his shoulder, tries to pass the checkpoint, ostensibly to tend his corn crop. The commanding officer lets him pass but insists on a daily music lesson. Can the old man ferry out the ammunition in his violin case under the soldiers' nose?
El Capitán Tronido, a handsome and reliable Mexican bandit, flaunts his ventures until the people of El Paramo demand that their Comandante Ruiz bring about his capture. Ynez and Juan, a poor but handsome youth, are lovers; but Ynez's father desires his daughter to marry Señor Morgan, a wealthy gringo rancher. Desperate at the thought of losing his Ynez, Juan goes to her hacienda by night and informs her that he plans to collect the reward for Captain Thunder so that they may be married. Meanwhile, Morgan, a rustler, meets up with the notorious bandit, who grants him a favor.