The film starts with the murder of Priti, wife of Shekhar (Aftab Shivdasani), a wealthy and well-known journalist. Inspector Lokhande (Ashutosh Rana) investigates the case and accuses Shekhar of the murder, saying he has enough evidence to arrest and convict him. However upon getting bail from the court, Shekhar asks his lawyer to fight his case for him however his lawyer tells him that he will not be able to fight his case because he is a corporate lawyer and only fights civil cases. He suggests Shekhar to ask Simran Bhargav (Lisa Ray), who is a very skilled criminal lawyer in his firm to fight his case.

Shekhar goes to Simran's house to convince her to take his case. Simran tells Shekhar that she'll defend him only if she is convinced that he is innocent. Simran is battling inner demons over a case in which she got a man convicted for crime he had not committed. Her guilt increases when she learns that the innocent man had committed suicide in custody.

While representing Shekhar, whom she considers innocent, Simran falls in love with him – a part of Shekhar's plan to win her trust. They end up having intimate, passionate and sensual sex. After the court declares Shekhar innocent, Simran spends the night with Shekhar at his house. The next morning, while opening his closet, she finds a typewriter hidden between sheets.

The significance of this typewriter is that there have been typed 'crank' letters sent to her office, leaving little clues that point the finger to the swimming coach Jimmy Parera (Vishwajeet Pradhan), who had an affair with Shekhar's wife. The typed letters all have a flyaway 't' on them.

Simran then comes to know that Shekhar is the real murderer. She leaves for the police station to give the typewriter she has found. Shekhar realizes this and is on the prowl to claim his next victim. In the end, Simran kills Shekhar in self-defense.

• Aftab Shivdasani as Shekhar Saxena
• Lisa Ray as Simran Bhargav
• Apurva Agnihotri as Amit
• Ashutosh Rana as Inspector Lokhande
• Irrfan Khan as Public Prosecutor Mehta
• Vishwajeet Pradhan as Jimmy Parera
• Divya Dutta as Payal Malhotra
• Prithvi Zutshi as Lawyer
• Sucheta Khanna as Shalini
• Kurush Deboo as witness, Rustam Sodawaterwalla,
• Pushkar Dwivedi as chotu

The music of Kasoor was composed by Nadeem-Shravan. The lyrics were penned by Sameer. Singer such as Kumar Sanu, Udit Narayan and Alka Yagnik lent their voices for the album. The soundtrack became very popular upon release. The soundtrack attained number 1 position on the all-time music sales music chart of 2001. The soundtrack received a rating of 8/10 from Planet Bollywood.

Track listing

The film received mixed reviews from critics. Taran Adarsh of Bollywood Hungama praised the performance of the lead cast saying, "Kasoor scores the most in that one important department — performances. Credit for this must go primarily to the two principal performers — Aftab Shivdasani and Lisa Ray — who come up with proficient performances."^[9] Aparajita Saha of Rediff.com stated, "this is a film that attempted an intriguing premise but failed when it didn't fully explore that very premise and take it to its logical and rightful conclusion."^[10]