In the blinding city of Lumina, casting a shadow is a crime, and repairing one is a deadly secret. Lumina is a metropolis built of bleached bone and polished obsidian, a monument to a singular, unwavering ideal: light. Here, darkness is illegal, and shadows are not merely absences of light—they are parasites. They feed on a person's hidden traumas until they detach, severing the host's sanity. Vesper is an "Umbra-Stitcher." Operating in the criminal underground, she uses a needle of starlight and thread of liquid mercury to physically sew detaching shadows back onto people's heels. She is cynical, exhausted, and burdened by the secret darkness her fellow citizens desperately try to hide. Mercer is a "Hollow"—a bounty hunter who casts absolutely no shadow. In Lumina, this should mean he is dead. He defies the laws of physics, claiming he didn't lose his shadow; he devoured it. He hires Vesper not for healing, but to help him track down the "Severed," rogue shadows that have killed their owners. Vesper is terrified of Mercer, yet when she touches him, her own rebellious shadow is finally calm. In a loud, bright city that demands perfection, his absolute emptiness is the only quiet refuge she has ever known. But Mercer is hiding a fatal truth: he is a living siphon, absorbing the city's darkness to protect others, and he is rotting from the inside out. As the ruling Illuminators close in, Vesper must make an impossible choice: let the darkness consume the man she is falling for, or perform the "Grand Stitch"—sewing their souls together to share the burden of a shadow massive enough to eclipse Lumina forever. Some shadows cannot be outrun. They must be worn.