Intro hints at some disturbance during a celebration in honor of a local government official, and next morning the bloodied, violated body of an unknown girl is found beside a railroad track.
Phitak Suprapdit identify the victim as Samnian, an abandoned wife who decided to catch a train upcountry to be reunited with her husband in the northern town of Uttaradit.
Macabre Case of Prom Pi Ram is a dramatization on a true crime that took place in a rural hamlet known as Prom Pi Ram (alternatively spelled Prompiram or Phrom Phiram — northwest part of Phitsanulok province in upper central Thailand) between July and August 1977, when the unidentified young woman's corpse is found abnormally by the railroad tracks.
The victim was a mentally ill woman who was raped by as many as 30 men in Prom Pi Ram and strangled her to death, then put her body on the track for the train to crush to disguise the case.
Finally there was a mediation where the filmmaker changed the title to Keunbab Prompiram (คืนบาป พรหมพิราม; "the night of sins in Prom Pi Ram").