When twenty-one-year-old Dominic is persuaded to rescue a young girl from the underground tunnels of Wupatki, the two find themselves lost in a strange realm of celestial enigmas, riddles, and otherworldly creatures. When Dominic arrives in the land of the dead, the underworld queen offers him passage home on one condition: he can't return as the person he was; he must leave parts of himself behind as he travels the underworld road. Hannah is eager to prove herself an expert at solving the zodiac's mysteries, but failure will lead to self-destruction, and unlocking the gate may unleash a powerful demon on her own world. Enigma is the first book in a trilogy, followed by Eridanus and The Secret of Ophiuchus.