The small South American republic of Guadalarma is under the rule of despot Don Salvador, surrounded by a civil guard, his mistress (La Morenita), his henchman (Don Ramón) and the fortress governor (the venal Don Gaspar). One morning, the city's French jeweler Michel Dumartin receives a visit from a client named José Llanos, one of the regime's fiercest opponents. Llanos is soon denounced and shot dead by Salvador's men. At the same time, Dumartin was accused of complicity with the rebels. Arrested and imprisoned in the fortress, he is ripe for the death penalty.