A disgraced, nameless detective wakes up in a trashed motel room with a lethal hangover and complete amnesia. After discovering he has lost his badge, his gun, and his mind, he meets Lieutenant Kim Kitsuragi. Together, they establish their temporary headquarters at the Whirling-in-Rags and take their first look at the gruesome murder case: a hanged man rotting in the backyard.

As the amnesiac detective tries to piece his identity back together, the duo interviews the eccentric residents of Martinaise. From local drunks to a corporate negotiator, everyone has a secret. Tensions rise as they attempt to cut down the hanged man for a proper autopsy, all while navigating a high-stakes political standoff with the powerful Union boss, Evrart Claire.

The broken water lock is finally repaired, opening up access to the vast, chilly coastline of Western Martinaise. The investigation widens significantly as the detectives interview new witnesses, explore an abandoned boardwalk, and look into the cryptozoological theories of a strange married couple. Pieces of the murder puzzle begin to drift into place.

With the coastal area fully accessible, the detective delves deeper into the supernatural and historical scars of Martinaise. An investigation into a supposedly haunted, doomed commercial area and a hollowed-out old church reveals how the past still grips the present, throwing the detective into a profound existential spiral.

The clock is ticking, and atmospheric pressure builds over the city. The detectives work tirelessly to tie up loose ends, chasing down desperate leads regarding the mysterious "Hardie Boys" and trying to track down the elusive weapon that fired the fatal shot. Every conversation feels like a chess match where a single wrong word could spark a riot.

All political and social friction in Martinaise reaches a boiling point. The unstable peace shatters as the mercenary tribunal commences. In a tense, chaotic, and bloody confrontation outside the Whirling-in-Rags, the detective's skills and morals are put to the ultimate test in a sequence that will change the fate of the district forever.

In the aftermath of the tragedy, the final clues point to a lonely, abandoned sea fort off the coast. The detective and Kim cross the water to confront the real killer—a ghost from a forgotten war. As the mystery is solved, the detective must finally face the mirror, receive his psychological evaluation, and accept who he has become.