Pidge and Matt are siblings, though growing up apart they never knew. Pidges uncle, Coran, to live with him and his daughter Allura. When Coran decides its time for Pidge to visit her real home, she ditches him and, by a lucky chance, meets Matt. They start talking and end up falling in love with each other. For Matt's 16 birthday the two go to the beach, no one else wanting to go as it was a little late. Matt's the first to jump into the water, and when the two find this pretty blue crystal, Matt miraculously turns into a merman. Any contact with water of any type will turn him. As they work their way around it, they find out that theyre siblings and that's when things get a littler harder for them. They decide to continue the relationship, and the non approvers get ignored. Will they be able to cope with keeping Matt's secret and there undying love for each other?