Archangel Gabriel returns to Willa Reese, the cancer patient who seems to be a magnet for Maledarchs. He's convinced that Willa—or someone in her life—is his connection to a high-ranking demon. However, if he doesn't uncover a clue before Willa passes away, he loses his lead.

Meanwhile, Archangel Metatron is living on Earth as a man named Ronald Glum. When he unexpectedly finds himself in a psych ward, he meets one of Willa's nieces, Kala, and launches of investigation of his own... and possibly a romance.

Like the previous book, School for Spirits: Hidden Warrior features a more adult set of characters.

Content warning: Suicide attempt