William Pope and his friends sign on the Rattler privateer whose mission is to seek out and destroy British merchant shipping during the American Revolutionary War. They attack a British nobleman's house in Ireland, take many ships in the English Channel, fight off a British frigate, and take a Royal Navy sloop-of-war. During rest and recuperation in France, William meets Pierre Didier, his wife, and their beautiful daughter, Louise. Williams enemy from the Felicity causes more trouble.

The Rattler cruises north to Holland and south to Portugal and then Morocco. After taking a Tripolitan pirate xebec, William is promoted to acting lieutenant, given command of the prize, and helps a bedouin sheik regain a fortress from his cousin. William and his friends save some castaways, including an English lady, and sail to the Canaries, where they reunite with the Rattler and William is permanently promoted to lieutenant`.