In 1847, a king embarks on a special journey – he has all the wealth in the world but what he’s seeking is peace of mind. In the depths of the forest, he encounters an enigmatic deity named Panjurli. This deity bestows upon him eternal peace and happiness, under one condition. The king must donate the land to the indigenous villagers. However, there is a haunting warning that accompanies this blessing. The king or any of his descendants must never attempt to reclaim the land, for it would awaken the wrath of the spirit known as Guliga, a mysterious and powerful force.
In 1970, a royal descendant defies warnings from the Daiva to reclaim the land and comes to a premature end, vomiting blood on the court stairs. Jump to 1990, when we meet Murali, a forest officer at a nature reserve. The villagers in the buffer zone fear their land will be seized by government officials and fiercely resist.
Enter Shiva (Rishabh Shetty), an accomplished Kambala athlete, and a good-for-nothing illegal poacher, and the son of the Bhuta Kola performer. (Bhuta Kola is a sacred ritual, which Shiva refuses to perform. This might have something to do with his last memory of his father, who disappeared into the forest while performing a Bhuta Kola.)
Murali devises a plan to apprehend Shiva and his gang, but the forest seems to be on Shiva’s side and Murali is the one who is injured in the process. Capitalizing on this opportunity, Shiva and his companions go underground to evade capture, ultimately returning to their village to reunite with their families. Regrettably, their respite is short-lived as they are apprehended by the police and forest guards the following morning.
All this time, Devendra, the village's landlord, has seemed like the good guy, but we now learn that he’s one of the bad guys. He tries to bribe Shiva’s brother into working with him to convince the villagers to give up their land — Shiva’s brother, Guruva, performs Bhuta Kola — but Guruva refuses. Devendra kills Guruva and turns his attention to Shiva. Manipulating Shiva's emotions, Devendra makes Shiva think Murali killed Guruva.
However, Shiva figures out the truth about Guruva and exposes Devendra's land-grabbing motives to the villagers. The revelation of Guruva's murder by Devendra ignites a call to action, uniting Shiva and Murali in a joint effort against the landlord.
A climactic clash ensues in which forest officials join hands with the villagers and fight Devendra and his army of men. In the bloodshed, several lives are lost. Devendra and his henchmen dominate the killings.
During the climax of Kantara, Shiva's connection to Panjurli becomes more pronounced as he strikes his head against Panjurli's stone, and seems to be possessed by Panjurli’s companion deity, the vengeful Guliga. Shiva becomes almost superhuman as he assassinates an army of Devendra’s men. Finally, he stands tall in front of the landlord and declares, “Did you forget the guide, Kshetrapala, the guardian deity? My lord Panjurli might have forgiven, but I will not. As a consequence of your deeds, by offering your blood to this soil, I shall upload its righteousness.” In one quick slash, he eliminates Devendra.
In the concluding scene, we see Shiva perform a Bhuta Kola and embodying Panjurli's spirit. Murali is in attendance, as are other villagers. Towards the end, he has the forest official join hands with the villagers over his chest – promoting unity and harmonious living in the future. The message is simple: So long as the inhabitants of the forest work together to maintain peace, the forest will thrive with them.
Then, unexpectedly, Shiva runs into the forest, just like his father had years ago. Much like his father had left his family behind, Shiva leaves behind an unborn child and the suggestion is that this child will continue the Bhuta Kola tradition. Panjurli will continue to intervene when human greed takes over. Equilibrium will always be restored.