Hana has always longed to have a pet of her own. So when a cat turns up at her bedroom window one night, she thinks her dream has come true. But Ace is no ordinary cat. He's a detective cat who has come to invite Hana to join the Moonlight Mystery Agency, and that's when the magical adventures begin! Join Hana and Ace on their first mission to solve the mystery of Spark the bionic unicorn's missing birthday cake!