While on a school trip to Spain, Boston and his classmates visit an outdoor market. Boston reaches for an item that catches his eye when suddenly, everything is different. Through a door in time, he lands in 1492, in the shadow of the Spanish Inquisition. There, danger is around every corner. He arouses the suspicions of the Spanish royal court and at the palace of Alhambra, where he falls into the cruel clutches of the Inquisition. But two new friends, Tariq and Salomon, threatened as a Muslim and a Jew, support him in this desperate situation. Boston must find a way back to the present time while making sure the course of history stays intact.