Strangers (2007)

Mr.Rai (Kay Kay Menon) and Rahul (Jimmy Shergill) meet on a rain journey. Rahul seems to have seen Mr. Rai's name in the passengers list. They start chatting. Rahul talks about his failing marriage to Priety (Nandana Sen). Rahul is a writer by profession and he cant write anymore. He lives on the earning of Priety. Mr. Rai talks about the loss of his 6 years old son and how that has driven his wife (Sonali Kulkarni) almost to the verge of being insane, thus spoiling his married life as well. They get drunk and soon enough Mr. Rai suggests a plan. Rahul would kill Mrs. Rai and He would kill Priety. They separate after this. Flashbacks show Rahul doubting Priety and accusing her of Adultery. Priety, tired of his accusations makes up her mind to actually commit it. She goes to a bar where she meets Mr. Rai. They go into a room to have sex after getting several shots of alchohol. Mr. Rai decides not to and sees Priety crying in the bathrooom. She reveals that she has been faithful to her husband. Mr. Rai gives her his visiting card and requests her to talk to him anytime she feels like. They become very close friends. After spending some quality time with each other they have an affair and land up having sex after all on a 'business trip' to Goa. They make plans to be free after and frame Rahul in the way. They plan a journey on the same train where Rahul will be sent by his wife. Rahul on the other hand keeps following her and knows everything. It is revealed that he knew all throughout who Mr. Rai is. He agrees to kill Mrs. Rai. Finally, Rahul is arrested by the police and he gives a set of bids to Mr. Rai while being taken away. He has killed Priety instead of killing Mrs. Rai, hence completing his revenge.