Ally Lancaster & The Gemstone Sirens (Paperback) (ISBN-13: 9798989703302)

With summer break coming to an end, it's time for Ally Lancaster to return to Willow Reins-the one-and-only school of dueling. After landing herself in a high-stakes battle to save the school during her first year, Ally can't wait to see what her second year has in store. However, when three mysterious second-year sisters go missing, things go from bad to worse very quickly. It's up to Ally and her friends to sail across the sea and rescue them from the dangers of Gelesca Cove. But as time goes on, Ally begins to realize that these triplets might not be as innocent as they seem.