1677. On a late-summer's evening, two ships lurk off the coast of south-west Ireland. Seventeen-year-old Hector Lynch wakes to the sound of a pistol shot as the Barbary corsairs raid his village, and he and his sister are snatched. Separated from each other, Hector is sold at auction in Algiers and thrown into a bewildering world where life is cheap and only the quick-witted survive.

In North Africa, Hector befriends fellow captive Dan, a Miskito Indian from the Caribbean, and the two men convert to Islam to escape the horrors of the slave barracks - only to become victims of the deadly warfare of the Mediterranean. Serving aboard a Turkish ship, their vessel is sunk at sea and by a savage twist of fate they are chained to the oar bench of a French galley.

Desperate to find his sister, Hector finally stumbles on the chilling truth of her destiny when he and Dan are shipwrecked off the coast of Morocco.