When struggling tattoo artist Lena Cruz takes on a mysterious client offering an unusual sum for a sigil she’s never seen before, she unwittingly opens a door between worlds—and binds herself to Kael, a brooding, immortal Nightborne cursed to live in shadows. Kael was only supposed to protect Lena until the sigil’s purpose was fulfilled. But as supernatural threats close in on them, and Lena discovers a latent power awakening within her bloodline, their bond deepens into something neither expected. In a city full of secrets, Lena and Kael must unravel the truth behind the sigil’s origin—and each other—before time runs out and Lena’s soul is claimed by the dark.