The Mysterious Cities of Gold is set in 1532, a time of great change in the New World. Esteban, a 12-year-old boy from Barcelona, has a unique connection to the Sun and wears a mysterious medallion that may be linked to the Mysterious Cities of Gold. After his adoptive father's death, Esteban learns he was rescued from a shipwreck as a baby and sets out to find his parents. Along the way, he meets Zia, an Inca girl with the same medallion, and Tao, a young Galapagos islander who claims to be the last heir of the Empire of Heva.