The Rubicus Prophecy: The Witches of Orkney, Book Two

As Abigail enters her second year at the Tarkana Witch Academy, she is up to her ears studying for Horrid Hexes and Awful Alchemy. But when an Orkadian warship arrives carrying troubling news, Abigail and Hugo are swept into a puzzling mystery when they help a new friend go after a missing item--one that might spell the end of everything they know.