As their investigation speeds up, a lawyer is killed in the same fashion as the politician and doctor before. Arjun deciphers that rather than trying to find the serial killer, it would be best to identify the person he is targeting next. As he gets down to work to try and stop the serial killer from killing yet another person, Arjun is in for a shock when he realizes that he himself is the next target. He then decides to find out what the reason could be for the serial killer to want him deed. The rest of the plot of Nibunan revolves around why the serial killer is targeting Arjun and what his motive was for to kill the politician, doctor and the lawyer.
Being Arjun's 150th film, the veteran actor has carried the entire film on his shoulders and has done a tremendous job yet again. Known popularly by fans as the 'Action King', he bonds well with the character written for him and he has yet again lived the role of a stylish investigative police officer this time. He looks good and displays an active personality throughout the film's narrative. His role is not just confined to playing a police officer, but also as a loving husband, a duty-bound father, a loyal friend and as an endearing friend. Prasanna, who comes in as a member in the investigative team headed by Arjun has played his role quite well. He has nailed the nuances of a policeman - be it in the physical form or in his mannerisms. Varalaxmi Sarathkumar has landed a meaty role and she has made full use of the opportunity.
Director Arun Vaidyanathan has made the film based on a tight and racy script that keeps us on the edge till the end. Rather than utilizing him as the action hero that Arjun is renowned for, the filmmaker has written a character that has more scope for performance. Likewise, since Arjun is the most dominant character in the script, other characters fall short in comparison at times. The whodunnit murder angle revealed in the climax is a treat and doesn't disappoint as many will not see it coming. S. Navin's songs are enjoyable, but it is in the background score department where he has hit the high notes. Arvind Krishna's cinematography skills come to the fore once again and the experienced technician has once again shot the film in a fitting manner.
In shot, Nibunan is a racy treat.