Young teenager Rab Burnside lives with Jesse his competitive brother and Buttons, their quixotic grandfather, on the windswept coast of Newfoundland during Queen Anne's War. One day, Buttons spots a mysterious ship sailing toward shore, doomed to crash into the shoals. Rab and Jesse scramble to save it and set in motion a series of events that take them on the trip of a lifetime. With their newfound ship and a family heirloom, a steel cutlass that can be used for maximum good or ill, the resourceful and determined Rab and Jesse, the youngest sailors of the Queen's Navy, and Buttons set off to rid the world of a crafty pirate named Captain Smallbeer. The mission takes the small band around the world, where they often come face-to-face with the sinister captain, who steals Rab's powerful cutlass. From the Sahara to the pampas to China, they must survive storms, battles and betrayal. Can Rab ever capture the evil pirate Captain Smallbeer, who vows never to give up the Lost Cutlass?