In 1808, the three children of Mario Monteleone, grandmaster of the Iron Knights, a secret society in Southern Italy, are kidnapped by a mysterious enemy. In 1815, Mario himself is arrested and executed. The Iron Knights then morph into the Companions of the Silence, which have sworn to avenge Mario, but eventually turn to crime. In 1823, a mysterious stranger walks into their midst, claiming to be the notorious bandit Bel Demonio, but in fact, he is Mario's eldest son, Fulvio. He then takes over the Companions and embarks on a mission of vengeance, while defying the traps laid for him by the diabolical Chief of Police, Johann Spurzheim.

Bel Demonio (1850) and The Companions of the Silence (1857), were retroactively linked by Paul FEval to his saga of the Black Coats, functioning as the backstory of that vast criminal conspiracy. The peak of development that he attained in The Companions of the Silence was so splendidly theatrical, that future exercises in a similar vein had no option but to take a step back and find new directions of development. The Companions of the Silence forms an important bridge between the author's earlier tales of heroic banditry and the pioneering exercises in crime fiction that began with John Devil (1862) and continued with the The Black Coats (1863-75).