In London, about the middle of the sixteenth century, the young Edward, Prince of Wales and son of Henry VIII, aged about twelve years, would like to escape the etiquette of the Court and have fun outside with Children of his age. At the same time, Tom Canty, poor kid of the streets, dreams of escaping his condition. Fate brings together the two children who, taking advantage of a striking resemblance, exchange their respective "roles", not without risks, for the Count of Hertford conspires against the throne: he attempts to have the Prince murdered In favor of his escapade, and to take Tom, now Edward, under his control. The intervention of a mercenary, Miles Hendon, makes it possible to defeat this conspiracy.