The story revolves around the unnatural death of a young woman named Manikyam (Mythili) in Paleri, a small village in northern Kerala, in late 1950s. Although it was claimed by her in-laws that she died after she had a seizure, examination of the body revealed it to be a case of murder. The police charged three locals with the murder, only to be released by the court which described the prosecution`s case as flawed. With no further investigation, the case had, since then, gone cold over the years, eventually acquiring the status of an unsolved mystery.
Around 52 years later, Haridas (Mammootty), a detective living in New Delhi, sets out on a journey to Paleri hoping to solve this mystery. Apparently, he was born in the same village on the same night when Manikyam was killed. He is joined by Sarayu (Gowri Munjal), a crime analyst. How the case unfolds, and how the mystery is solved forms the crux of the plot.