The Other Side (Descendants 2; Carlos De Vil)

When the pressure to be royally perfect gets to be too much for Mal, she returns to the Isle of the Lost. She discovers that Uma, the daughter of Ursula, has taken over as queen, and that her gang is finalizing plans to bring down the barrier. Princess Esmeralda joins the VKs and King Ben to the Isle of the Lost to stop Uma and her gang from bringing down the barrier, but along the way a certain Snow Queen causes a blizzard of destruction and misery to the young ice princess and her friends.

CHECK OUT THE FIRST BOOK IF YOU HAVEN'T ALREADY! ITS CALLED 'LET IT GO'