During a party at Monster High, a strange force pulls Lagoona Blue, Frankie Stein, Draculaura, Clawdeen Wolf, Toralei Stripe, and Gillington “Gil” Webber to the Great Scarrier Reef. It is here that Lagoona must confront her childhood memories, get over her stage fright, and deal with her old enemy Kala Mer’ri as well as the threat of the Kraken that lives nearby.