The Cay is a novel about Phillip Enright, a boy who is stranded on an island with Timothy after his ship is torpedoed during World War II. Phillip has been blinded from an injury and must rely on Timothy to help him. However, Phillip is is prejudiced against Timothy, who is black. Over the course of the book, they develop a strong friendship, surviving on their small remote island. In the end, Timothy dies in a hurricane, Phillip buries him and is rescued, receiving surgery to repair his eyesight.
When World War II breaks out, 11-year-old Phillip Enright and his mother board the S.S. Hato to Virginia because his mother feels it's unsafe to stay in Curaçao with the German submarines surrounding the area. The ship is torpedoed, and Phillip is blinded shortly after a blow on the head by a piece of timber and is stranded in the sea with an old black man named Timothy and a cat named Stew Cat.
Drifting at sea, they soon find an island in Devil's Mouth and build a hut while keeping track of the days by putting pebbles in a can. With few supplies, they live alone together for two months, fishing and collecting rain water. The cay is only 1 mile long and 1/2 a mile in width.
Initially, the pair display significant difficulty in being able to tolerate and work with each other, often because of young white Phillip's racial prejudice against the elderly black Timothy. Phillip learns to overcome his disdain for Timothy and develops a strong bond of friendship by the end of the novel, as Timothy takes care of Phillip and teaches him to survive independently, to the point where Phillip doesn't need him anymore.
Planes fly over the cay, but they do not see Timothy and Phillip, lengthening their time stranded there. After a hurricane hits the cay and Timothy dies "from being tired", Phillip, devastated, digs a small grave for him. He is left with only Stew Cat.
Phillip is then rescued by a navy vessel and one year after he and Timothy find the island, he has many surgeries to get his sight back. In the end, Phillip decides he will become a sea explorer and travel to multiple islands and soon hopes to find the Cay he and Timothy had been stranded on, which he is certain he will be able to recognize by closing his eyes.