Lagoona Blue (Larissa Galagher), with her sea-monster heritage, takes center stage in MONSTER HIGH: GREAT SCARRIER REEF. Toralei Stripe (America Young), competitive, sneaky, and jealous of Lagoona, discovers that her rival is a wonderful dancer struggling with a bad case of stage fright. Eager to capitalize on Lagoona's weakness, Toralei embarrasses and bullies her on the Internet. Lagoona fights back, and the two end up struggling in a churning whirlpool. When some of the other ghouls (Clawdeen, Gil, Draculaura, Toralei, and Frankie Stein) jump in to help, they're transformed into sea creatures and sent deep into a wondrous ocean habitat. There, in addition to meeting Lagoona's strange family and other denizens of the deep, they discover that to regain their natural forms and return home, Lagoona must acknowledge her darkest fear and confront it. It's a challenging mission, made even more treacherous by Kala Mer'ri, a mean-spirited Siren of the Sea, along with the Kraken, a legendary sea serpent. Fortunately, Lagoona Blue is strong and determined, and she's not alone. As always, the ghouls from Monster High work together to confront the fragile Lagoona's darkest fear, make surprising new friends, and win the day.