• Composer : Pritam Chakravarty
• Lyricist : Amitabh Bhattacharya

Satya Chaudhry (Sonakshi Sinha) is told by her doctor that she has cancer and will die soon. She goes back to her native village in the Rajputana area and requests her childhood acquaintance, Roop (Alia Bhatt), to provide companionship to her husband, Dev Chaudhry (Aditya Roy Kapoor) who runs a liberal newspaper. Roop keeps rejecting Satya's proposal but later gets convinced by her father, Dharampal (Pawan Chopra), and agrees on the condition that she will marry Dev to which Satya agrees. Once married, Dev tells Roop that he still loves Satya and that their relationship will only be cordial and platonic. A depressed Roop takes solace in music, which she begins by learning from the madam of a brothel, Bahaar Begum (Madhuri Dixit). She also begins working in her husband's publishing house, to use her education to her advantage. Roop expresses interest in writing about the condition of the locality in which the brothel is located, during which she meets with a womanizing blacksmith named Zafar (Varun Dhawan). Zafar wants to exact revenge on his parents, Bahaar Begum and Balraj Chaudhry (Sanjay Dutt), (who abandoned Zafar after ending his extramarital affair with Bahaar), by seducing Roop, as she is married to Balraj's legitimate son, Dev. Roop misconstrues Zafar's intentions and falls in love with him. She also begins to develop a friendship with Dev, much to Satya's happiness and sadness. Satya dies after urging Dev to give Roop a chance and to forgive Balraj for his affair. In another effort to humiliate Balraj, Zafar instigates communal hatred in his friend, Abdul Khan (Kunal Khemu), by demanding for the partition of India on religious lines, which Balraj and Dev do not support. When Balraj becomes aware of Roop and Zafar's affair, he confronts Bahaar and Zafar. Bahaar, who disagrees with Zafar's approach, warns Roop and tells her about Zafar's real intentions. Heartbroken, Roop consummates her marriage with Dev but insists that she would never be able to love him. As Abdul's political stance gains leverage, riots against Hindus and Sikhs in the city take place, during which the Chaudhrys decide to flee to Amritsar with the help of Zafar, but not before Saroj (Achint Kaur), the benevolent maid is brutally stabbed to death. Zafar confesses to Roop that he eventually fell in love with her, despite his early intention. While boarding a train, Zafar is stabbed in his stomach several times with a dagger by Abdul, as Roop and Dev escape. Ten years later, Roop and Dev are interviewed about their experience by Aditya (Pavail Gulati), a journalist documenting the partition. The story ends with Roop remembering Zafar and Roop's inner voice saying that the colour of love and hate is red, but it's love that often gets stigmatized or blemished.

Hindi with English Subtitle

• Track 2 : Kalank – Title Track ( कलंक - शीर्षक ट्रॅक )
• Track 3 : Tabaah Ho Gaye ( तबाह हो गये )
• Track 4 : Aira Gaira ( आयरा गैरा )