Kanchana 3 is a horror comedy film that revolves around Raghava's (Raghava Lawrence) family. He lives with his mother, Brother, Sister-in-law and niece. For a family event, they go to Coimbatore and his cousins also join them there. Things go smoothly until Raghava starts to notice some strange incidents in his grandfather's place. He is very scared of ghosts and thus becomes the main target for possession. Even his family and cousins start to notice the change in Raghava's behavior. They try to do everything to get the ghost out of their dear son's body. But things take a turn when they find out who the ghost is. Kaali (Raghava Lawrence) was a just and sincere man. He ran an ashram for those who had nothing and also funded the education of poor youth. He was praised and appreciated by many. He was immensely in love with Rosie (Ri - Djavi Alexandra) who reciprocated his feelings. Life was peaceful until a ruthless politician, Bhavani (Kabir Duhan Singh), entered his life. Then the story focuses on Kaali's life when he was alive and what led to his death. How was Rosie killed and what happened to the ashram and people in it? After knowing the truth about Kaali, what will be the reaction of Raghava and his family? This forms the rest of the story.