Summerland introduces itself on Clam Island, an island off of the west coast of the United States. In a particular corner of the island is a place that the locals call the Summerlands, where it has never rained a drop any year in history from June to August. Ethan Feld is an eleven year old that moved to the island with his father just after his mother died a sudden death. The theme of baseball comes into the poem when Ethan finds out that he isn't good at it, despite encouragement from his father and loads of practice. On a baseball team, he proves to be the worst player ever seen.
Things start to change when Ethan dramatically meets Cutbelly, a werefox that visits him. Cutbelly explains that Ethan is living in only one of four existing worlds, and the one that he is in now is nicknamed the Middlings. The other three worlds are the Summerlands, the Winterlands, and the Gleaming. Cutbelly explains that it never rains in the Summerlands because two leaves of the Tree of Life are so close that two worlds exist there simultaneously.
Trouble starts to happen when Coyote (who is known by many other names, including Satan), has an idea to poison the Tree of Life, the Tree that holds the whole universe in order. Ethan and his friends Jennifer and Thor work together to stop Coyote. They travel from world to world to stop Coyote, and Ethan uses baseball to ultimately stop him.
Summerland is a book with lots of symbolism and mythology since it is has ideas like other worlds. Many of the characters and ideas are symbols that were originally developed in ancient mythology. The story is filled with action as Ethan travel from world to world to ultimately end Coyote's evil plan.