Rafe Ryder and the Brushstroke of Time - L. L. Reynolds - Bog

Just when thirteen-year-old Rafe Ryder thinks his year can't get any stranger, he is proven wrong. After he and his classmates have averted a plot to destroy the elite angelic training ground known as Mystfira, as well as the very heavens themselves, Rafe is left to grapple with his newfound identity and figure out a way to get himself and the other Ryder-Knight students home to Earth. But when his friends start disappearing one by one, Rafe must take action. Are his friends alive? Have they fallen victim to the treacherous world of Mystfira, or to a more nefarious plot conjured by the dark spirits in Baeldavar? Along with a crotchety leprechaun named Seamus, Rafe and his two remaining friends must reckon with Time itself to solve the mystery before their classmates are lost forever.