In the early 18th century, the bandit Fra Diavolo returns to his camp in Northern Italy to tell his gang members about his encounter with Lord Rocburg and Lady Pamela. Disguised as the Marquis de San Marco, he rides with them in their carriage and charms Lady Pamela into telling him where she hides her jewels. He orders his thieves to ride to Rocburg's castle and steal his belongings and Pamela's jewels. Meanwhile, Stanlio and Ollio have also been robbed, whereupon Stanlio suggests to Ollio that they should become robbers themselves. After an unsuccessful attempt to rob a woodchopper, the duo encounters Fra Diavolo, who orders Stanlio to hang Ollio for impersonating him. Diavolo is then informed that his men have stolen Lady Pamela's jewels but have not brought the 500,000 francs hidden by Rocburg.