Discover the secrets hidden within the Marauder's Map with this heat change mug inspired by the Wizarding World of Harry Potter! The Harry Potter Marauder's Map Heat Change Mug shows one image when at room temperature, and then reveals the iconic Marauder's Map whenever a hot drink is added. Features the phrase that reveals the map's secrets in the popular books and films " I solemnly swear that I am up to no good!" This mug is a fun nod to one of the most iconic magical artefacts to be found at Hogwarts. Hand wash only. Not dishwasher safe. Do not microwave.