JJ's life has been miserable ever since his ill mother had to give him up. The only two good things he has are his best friend Sophia and his wonderful talent for music. Determined to know what happened to his mom, the young man escapes from his foster mother, a woman who encourages her charges to steal and bully. Following his memories, he takes shelter in Central Park. JJ becomes the new protégé of the Guardian, a homeless eccentric and self-appointed King of Central Park who promises to protect the boy and offers him the companionship of a dog called Mutt in exchange for food. Also, JJ's path crosses with Rebecca Cairn, another eccentric who lives in a brownstone overlooking the park. She takes particular interest in him, as does her estranged husband Noah Cairn who is always rescuing Rebecca when she grows depressed. JJ tries to shake off the help of these characters, thinking that his life would be better on his own. However, JJ's foster mother is looking for him, making his search for his mother dangerous. His growing relationship with the Carin's teaches him the truths about loss and letting go.