Carole Barrowman & John Barrowman 
Nephilim [EPUB ebook] 

Seventeen-year-old R my is a Conjuror someone who can alter reality with his music. But such a talent comes with a price. He and his superpowered friends, Matt and Em Calder, are engaged in a dangerous battle to save humanity as we know it. If they are to succeed, they must first decide who to trust. An amoral seventeenth-century artist? A quick-witted gang leader? Or a nephilim, half angel and half human, with silver-flecked wings? But time is running out. The friends must take action soon. For when fallen angels rule, chaos will reign.