This book picks up right where the last one left off - Daphne is trapped in the Underrealm and Haden, Rowan, and Ren have been exiled to the mortal realm. Haden finds his way back to their friends - Joe, Jonathan, Lexie, and Ethan, and they begin a plot to find Jonathan's bow and rescue Persephone from the Skylord prison. When they arrive, they are not able to find Persephone, but do find the bow and Jonathan's long-lost wife Psyche. Unfortunately, Haden was shot with the black arrow, and is slipping into despair without Daphne having delivered the full cure. Meanwhile, Daphne learns that Garrick's plan all along was to release the Keres, and she makes a plan to escape the castle, warn the others, and save Haden. Along the way, she meets a Shade who helps her and learns that she is a worthy heir of Persephone, able to wield her pomegranate necklace. She is able to get back to and save Haden, and together they will need to figure out a way to save not only the Underrealm but all realms from the terror that is the Keres.
This was actually my least favorite of the trilogy. Adding in Tobin's chapters didn't really add much for me, and I found all 3 narrators indistinguishable from each other. Aside from that, the plot was a little more than a little bit ridiculous, and full of things that pulled me out of the story. For example, after only 2 days in the Underrealm having not eaten anything, Daphne's clothes are already hanging off of her? I have had some gnarly stomach bugs where I don't eat for two days, and that's hardly enough to notice a difference in the way my clothes fit. Also, it was painfully obvious exactly who Shady was, so I don't know how anyone was surprised when Daphne revealed his identity. In addition, I thought the black arrow was supposed to be some sort of metaphor for depression, but if so then it was poorly done and if not it was just laughably dramatic. Finally, it felt like it wrapped up too neatly at the end. The relationship between Haden and his father was very similar to that in another book I recently read - Tarnished Are the Stars - but handled without any of the nuance or depth in that book. The author might as well have written "and they all lived happily ever after" at the end with how saccharine it was. Overall, not my favorite and I would much rather just reread Percy Jackson ad nauseum.