In the bioluminescent, star-worshipping city of Astraea, inventor and occultist Lucia Fairfax harvests a particular currency from the shadows―luck itself―drawn from a dimension she calls the Otherside. But when her latest ritual fails and her husband dies tragically, her carefully cultivated fortune bleeds dry.

Lucia’s desperate to restore her power, but her next ritual goes catastrophically wrong, summoning something far more Altair, a cosmic entity born of an ancient constellation. He is both human and not―impossibly seductive, unnervingly sentient, and the key to restoring what she’s a way to the Otherside.

Crossing into Altair’s realm is the most dangerous thing Lucia has ever done―and the most irresistible. There, she unravels the intoxicating secrets of the Otherside, the disturbing truth about her abilities, and the terrifying depth of his hunger. But with each revelation, escape slips further from reach. Trapped between worlds, Lucia must confront a devastating Love, desire, and ambition all have their price. And Altair is eager to collect.