Having plunged into Tartarus at the end of the last book, The Mark of Athena (2013), Percy and Annabeth struggle toward the Doors of Death, while their friends hurry to meet them on the other side at the titular House of Hades.
Riordan is most successful in his evocation of Tartarus and its hellish, monster-infested landscape. Without lightening his heroes’ miseries in any way, the author provides a helper and necessary mood-lifter in the person of Iapetus/Bob, the Titan whose memory Percy had obliterated with the waters of Lethe in a previous adventure. Now Hades’ janitor, Bob, along with a skeletal saber-tooth kitten he names Small Bob, joins Percy and Annabeth on their trek, causing them both to plumb unexpected moral depths. Meanwhile, on board (and off) the Argo II, Jason, Piper, Leo, Hazel and Frank similarly must come to understand themselves better in order to accomplish the tasks set before them (though not to equal extents). Though Riordan doesn’t stint on action or laughs (fart jokes abound, and a tart-tongued Calypso is a special treat), readers may find themselves appreciating these moments of contemplation all the more for the depth of characterization they reveal. The denouement finds the demigods poised for the final battle with Gaea and her minions; they have exactly 14 days to save the world.
In this adventure, victories are hard-won and the essence of bravery nuanced, making the journey as satisfying as it is entertaining. (Fantasy. 10-14)