Adventurous in her youth, Cassandra built gateways between Domhan and its parallel realm of Earth. Now she's too old for that kind of thing. But something is making it easier for demons to pass into Domhan. Not only that, but their behavior becomes inexplicable: whenever Cassandra banishes one, it laughs at her rather than resists, and it promises it will soon devour her essence and that of every resident of her small village. Cassandra is certain such a thing is impossible, for strong wards protect her village. But then Cassandra's granddaughter Aine falls through an unstable gateway. Cassandra is the only one within a hundred miles capable of creating a gateway and bringing Aine back. Despite her aching joints, Cassandra goes after her, and the gateway lands her in New Orleans. But something goes wrong with her tracking spell, which indicates Aine exists in four different places at once. As Cassandra struggles to find the true location of her granddaughter in the Big Easy, she discovers the source of the demons' confidence. Now, with an unlikely pair of allies-her timid granddaughter and a homeless man who may or may not be crazy-she has to not only save her granddaughter but also prevent both Domhan and Earth from being overrun by demons.