Jem and Nai may be twins, but as two halves of a split soul, they are as different as night and day. After losing their lives in a boating accident, the teens are recruited by Order to replace the recently departed Guardian of Blackbird. Their job? To protect and save the souls of the lost before they fall to the Discordant. A simple task under ordinary circumstances, but the town of Blackbird is far from ordinary.

It would be bad enough if their arrival simply coincided with that of a wraith, a rare and nearly impossible to catch Discordant. But the teens must also contend with souls that won't stay saved and adults who don't trust them, all while keeping up the appearance of normal high school seniors. And just because the universe hadn't finished piling it on, a local mystic reveals that the twins' worst enemy may be each other.

Jem and Nai soon discover that they are just as anomalous as the town they have been assigned to protect and can't help but to question the supposed infallibility of the Creator. After all, who in their right mind would put the fate of the world into the hands of teenagers?