Nun of My Business

When a Faerie nun shoves a piece of music under Vern's nose and insists it's an evil spell, he has some doubts as to her mental stability. But work is scarce for a dragon detective on the wrong side of the Interdimensional Gap, and if Sister Grace McCarthy wants to pay his bills for a wild goose chase, who is he to argue? Unfortunately, Vern is not the only one with concerns about Grace's sanity. When a child accuses the nun of hexing her voice, the city is in an uproar, and Vern has to uncover the truth - for Grace, for himself, and for the fate of the Faerie and Mundane universes.

Is the song just annoying? Or is it a summoning spell from the depths of hell? And how does a shell-shocked nun who refuses to sing fit in the equation - and Vern's life?