Reinstated to the Homicide Division and transferred to a precinct in Tokyo, Inspector Iwata is facing superiors who don't want him there and a recalcitrant partner, Noriko Sakai, who'd rather work with anyone else. After the previous detective working the case killed himself, Iwata and Sakai are assigned to investigate the slaughter of an entire family, a brutal murder with no clear motive or killer. At the crime scene, they find puzzling ritualistic details: Black smudges. A strange incense smell. And a symbol -- a large black sun. Iwata doesn't know what the symbol means, but he knows what the killer means by it: I am here. I am not finished. As Iwata investigates, it becomes clear that these murders by the Black Sun Killer are not the first, nor the last, attached to that symbol. With few allies, Iwata tries to track down the history of the black-sun symbol, puzzle out the motive for the crime, and connect it to an unsolved case in the past. Haunted by his own past, his inability to sleep, and a song, "Blue Light Yokohama," Iwata knows time is running out and he'll either be taken off the case or there will be more deaths."