Tide Stealers (The Sunken Kingdom, No. 2)

AFTER RESCUING UNA from the witch princess, Asa and Rollo are once again safe in Two Hills Keep. Asa is curious about the Moonstone Star and its magic, which she inherited when her mother was murdered. But when Asa tries her hand at her first spell, a band of underwater pirates called Tide Stealers appears and steals the jewel away! In order to get it back, Asa and Rollo must face malevolent ghosts, nasty sea giants, and one particular Tide Stealer who may hold secrets about their past.