Nine-year-old Cesar lives with his mother and grandfather in a remote fishing village on the Pacific Coast of the Baja Peninsula. Each morning, the boy and his grandfather, Abuelito, go to sea to catch baitfish that they sell to captains of tourist-laden sport fishing boats. Cesar yearns to crew on the boats—which he calls “white boats” for their gleaming white fiberglass hulls—just as his grandfather did when he was a boy. Cesar and Abuelito also share profound gratitude to the ocean for providing sustenance to their family for generations. They collect plastic debris that they find on the water and bring it to shore. ​ After Abuelito is tragically killed, Cesar takes the small skiff far out to sea to pursue his dream of catching a trophy blue marlin. His quest takes an unexpected turn when he encounters a humpback whale that has been ensnared in plastic fishing net and close to death. The boy risks life and limb to free the humpback from the plastic debris and becomes separated from his skiff. Now he must find a way to survive alone on the open ocean—save for a pair of tiger sharks that have been keeping a close watch.