A Spanish armada, led by Don Alonso Perez de Guzman el Bueno, is sailing to invade England when they hit bad winds and lose most of their crew to disease and desertion. Don Alonso tasks his remaining crew with impressing young men from the surrounding countryside from where they docked. One such young man is Manuel, a Moroccan orphan living in a monastery. He did not want to come along, but quickly learns sailor skills. As time progresses, Manuel grows close with his crewmates.

As the weather grows colder, Manuel becomes sick. It takes a long while for his fever to break, and when it does he is severely emaciated. He slowly regains strength, but is not yet strong enough to help out onboard the ship when they first spot the English shore. Though still recovering and fearing death, Manuel does his best in the first battle against the English ships, lighting fuses for the cannons. After the fever he is able to see people's auras, and especially notices when the auras would waft away into the air as people died.

The multi-day battle is intense and devastating. Most of his berthmates, those he shared a room with under the decks, die when a mast falls on them. At one moment, Manuel's patron saint Anne appears before him and deflects a cannonball that was about to hit his head. He says a quick prayer and continues helping in the fight. After it calms down, the armada retreats to the Flemish coast. The English follow in the night with fireships designed to burn down the remaining Spanish fleet. Manuel's ship barely escapes, but the armada is broken for good.

They decide to try and sail around the north of Scotland rather than try to get past the English ships in the Channel again. The attempt seems just as deadly as another battle, with many men dying of the cold, dysentery, malnutrition, and dehydration. His overseer and first friend on the ship, an Irishman named Laeghr, teaches him an Irish phrase just before passing, making Manuel swear he will never forget it. Later, the friar who cared for Manuel when he was sick leads him below decks to a room where the Catholics of the ship hold a ceremony for the lives of all those lost and took the Communion one last time before their expected deaths.

A huge storm his the surviving ships just as they turn south to head back to Spain and blows them to Ireland. Men approach Manuel as the ship is battered against the waves, thinking he is blessed and asking for his touch. When he does so, they are immediately taken to Heaven. The ghost of Laeghr visits him, telling Manuel to remember the words he'd taught him. The ship finds a bay that was protected from the storm, and the survivors make for shore. There were already English soldiers there, however, who were cutting down whoever they could see. Manuel knew that Saint Anne would protect him, and passes out on the beach. In the morning, the dead crew members are being eaten by wolves and birds, Manuel the only survivor. When a group of Irish people approach him, Manuel utters the phrase Laeghr taught him, asking for and receiving mercy.