"Conor, Abeke, Meilin, and Rollan are prisoners. Framed for a crime they didn't commit, the four young Greencloaks have been captured by the ruthless Oathbound. Rather than facing trial with the rest of their order, the friends and their spirit animals find themselves smuggled to a remote palace. There they discover that the plot against them runs deeper -- and is far more sinister -- than anyone realized. Someone has been manipulating both the Greencloaks...

Fifteen-year-old Billi SanGreal has grown up knowing that being a member of the Knights Templar puts her in danger, but if she is to save London from catastrophe she must make sacrifices greater than she imagined.