R.L. Ferguson 
Secrets and Shadows [PDF ebook] 

Superhuman kids, a missing girl and a thousand-year-old mystery. The gripping adventure begins… Finn’s world is turned upside down when he and his older brother, John, are ripped from their normal lives and sent to Alyxa, an island school that doesn’t appear on any map. As the unusual lessons at Alyxa begin, the brothers learn about their super-senses, but nothing can prepare them for the perils to come. To conquer their fears, they must master their senses…