Set in present day Banaras, the plot of Masaan follows two seemingly separate story arcs that eventually converge. The first of these tells the story of Devi. The film opens with her and her fellow student, Piyush, checking into a hotel room. They are interrupted when the police bursts in, accusing them of indulging in “indecent behaviour”. As the inspector records barely clad Devi on his mobile phone, the boy locks himself in bathroom and commits suicide. Devi and her family are subjected to blackmail by the police, particularly one Inspector Mishra, who demands a hefty bribe from Vidyadhar Pathak, Devi’s father. While he struggles to fulfill his demand, she responds in a dignified manner to the ‘stigma’ forced on her switching jobs. She eventually gets a government job in railways in banaras. Marred by the parochial mindset of people she leaves banaras and joins a course in Allahabad.
The second narrative concerns Deepak, a young boy (also from Banaras) from a low-caste corpse burners family working at the Burning ghat with funeral pyres.Despite a Corpse Burner Deepak wants to fly from the barrier subjected to a corpse burner and he studies Civil Engineering at a Polytechnic and here Deepak meets and falls in love with Shaalu, an upper caste girl.They start meeting each other and in one trip to Allahabad at the banks of Ganga, Shaalu falls for deepak and accepts his proposal, back to Varanasi deepak tells her about his caste and the work he does of burning corpse, but Shaalu remains firm and tells him that she is with him even if her parents refuse and asks him to attend his placement session well and bag a job.Even as she reaffirms her commitment to him she meets with an accident during a pilgrimage trip along with her family and dies ending up at the same cremation ground. The shattered Deepak loses all purpose in his life for a while. But eventually comes to cope with the support of his friends. He gets a job in railways also landing up in Allahabad.
The film reaches its climax as Devi comes to the bank of Ganga to immerse the gift her boyfriend had given to her on the fateful day in the hotel. Deepak notices her crying and offers her water to drink. A boatman beckons offering them a ride on the boat towards Sangam. Both board the boat striking a conversation. Devi tells Deepak that this is her first time she is going towards Sangam. Deepak tells her he has been there earlier once but adds that there is a belief one should accompany someone if visiting it for second time.