The Happy Mask side quest is a trading quest from The Legend of Zelda: Ocarina of Time. It begins when Link shows the soldier at the Death Mountain Trail Starting Point Princess Zelda's letter, allowing him to scale Death Mountain, and the Hyrulean Soldier asks Link to bring him a popular mask for his son. At the end of the side quest Link earns the ability to borrow the Mask of Truth, which allows him to listen to the secrets of the Gossip Stones scattered throughout Hyrule.