Kolaiyuthir Kalam when translated literally into English it means the Autumn of murders. It is a thriller serial based on the novel of the same name by
Sujatha Rangarajan. It is an interesting story, that reintroduces the duo of Ganesh and Vasanth. The story involves rash of deaths, similar to the fall of leaves from trees in Autumn. Thus the serial is rather aptly named. The story is based in the early 80's, a period of scientific and rational development. The plot starts with Ganesh and Vasanth visiting a town to solve a legal dispute, which involves settling some contention with a persons’ inheritance.
Here they meet a man, Kumara Vyasan, who is the guardian of an innocent heir, a girl named Leena. According to the conditions of the will the property cannot be divided or sold until the direct heir reaches her adulthood, at eighteen years of age, while close relatives will act as the holders of the inheritance until then. While discussing the issue, Ganesh and Vasanth are told that the Leena (the legal heir) has committed a murder, and has become a blood sucking vampire. They are told that she has concealed the victim's body by burying it two years previously. Ganesh and Vasanth are told that the town holds the belief that there is a spirit that periodically attacks the village every two years.
Ganesh is not willing to accept this as fact and searches for a valid and rational explanation. He goes with Vasanth and visits the farm at night, where they see an illusion resembling the girl Leena (but grey in colour) they also hear voices that seem call out a few names. This is just 1 of the many supernatural events that happen at the farm house on that night. Ganesh is forced to believe in the existence of the paranormal due to this experience even though he did not believe in them beforehand, while Vasanth starts believing in the existence of an angry Spirit. KumaraVyasan is completely sure that Leena (the heir) committed the murders, under the influence of the spirit. Ganesh doubts his words and starts to feel that the incident was master-minded by Kumar Vyasan to eliminate Leena and acquire her inheritance for himself if Leena dies without any viable heir.
A large number of murders occur while the investigation is underway, but surprisingly Ganesh finds that Kumara Vyasan is also one of the victims. At this point, Ganesh and Vasanth split while Ganesh attempts futilely to prove that all the murders were committed by humans, and the existence of the spirit is just a cover for the fugitives.During this time Vasanth tries to prove the exact opposite, he attempts to prove that the murders were the culmination of paranormal forces. All the circumstantial evidence points Leena being the killer, but her childlike innocence confuses Ganesh and causes him to doubt his conclusions.
As the book proceeds, we see that all scientific evidence collapses and Ganesh starts to suspect that the perpetrator is indeed a vengeful ghost. The serial follows their investigations as it leads them down a path where logic and reasoning do not lead to answers, and Ganesh and Vasanth are forced to consider the fact that perhaps the supernatural may not be as far-fetched as they initially thought.