Budo is lucky as imaginary friends go. He's been alive for more than five years, which is positively ancient in the world of imaginary friends. But Budo feels his age, and thinks about the day when eight-year-old Max Delaney will stop believing in him. Some say Max has Asperger's Syndrome, but most just say he's "on the spectrum. " None of this matters to Budo, who loves Max and is charged with protecting him from the class bully, from awkward situations in the cafeteria, and even in the bathroom stalls. But he can't protect Max from Mrs. Patterson, the woman who works with Max in the Learning Center and who believes that she alone is qualified to care for this young boy. When Mrs. Patterson does the unthinkable and kidnaps Max, it is up to Budo and a team of imaginary friends to save him -- and Budo must ultimately decide which is more important: Max's happiness or Budo's very existence.