Theevram opens with a crime where a young man is beaten to death with a club in front of his fiance. Then comes an investigation officer Alexander (Sreenivasan), and an assistant (Vinay Forrt). Alexander unlike the assistant, is an officer who doesnt believe in torturing the accused people to prove crimes. He is touted as one of the toughest cops in the service to get deceived. Though he is a man who even fears to witness a live postmortem, he is intelligent enough to prove crimes. He proves this one too without much problems. Parallel to this, we are shown another crime. Harsha Vardhan (Dulquer Salmaan) is a man of mystery. He lives lonely in a big house, and teaches music to one kid. Apart from the role of a musician he has one more role to play in life – that of a sadist killer. The film takes a U turn post interval, which zoomed in to story that took place four year back. There we can see Harsha as an aspiring young musician. The struggles that he has to face in the initial years of his career are shown here. Not only in his career, but also in his life too he was seen struggling to maintain his relationship with the lover. Then his wife is murdered and how he plans to set revenge on the one who murdered his wife.