Lahore, 1946: After receiving the devastating diagnosis of cancer, Satya Chaudhry (Sonakshi Sinha) returns to her roots in a small village in Rajputana. Understanding that her time is limited, she seeks out her childhood friend Roop (Alia Bhatt) to look after her husband, Dev Chaudhry (Aditya Roy Kapur), who manages a progressive newspaper. Roop agrees, but only on the condition that she marries Dev, a proposal Satya reluctantly accepts.
Once married, Dev confesses to Roop that his heart remains with Satya and their relationship will be purely platonic—a revelation that deeply saddens Roop. In search of comfort, Roop turns to music, learning from Bahaar Begum (Madhuri Dixit), the madam of a local brothel. Despite being warned against visiting the brothel, Roop threatens to take her own life, compelling Satya to advocate for her permission to pursue her passion. Roop also takes a position at the publishing house run by her husband, expressing a desire to write about the local community and its struggles, leading her to cross paths with a charming yet reckless blacksmith named Zafar (Varun Dhawan).
Zafar harbors a vengeful agenda against his estranged father Balraj Chaudhry (Sanjay Dutt) and Bahaar, motivated by resentment stemming from a past affair. Seeking to get back at Balraj, he tricks Roop into falling for him, manipulating her feelings under the guise of affection. As Roop and Zafar grow closer, she also develops a friendly bond with Dev, which pleases Satya. However, their fragile happiness shatters when Satya passes away, urging Dev to embrace Roop fully and forgive Balraj.
Yet, the specter of political unrest looms large as Zafar seeks to exploit communal tensions for personal gain. He enlists Abdul (Kunal Khemu), his friend, to stir hatred among the community against Dev and Balraj, who oppose the idea of partitioning India. Zafar manipulates the narrative, claiming that their opposition is rooted in their self-interest, which further deepens the religious divide.
Balraj, noticing the growing turmoil, warns Dev to tread carefully, but Dev remains steadfast in his pursuit of progress through his newspaper. As communal violence escalates, Balraj realizes the implications of Zafar's intentions and confronts him. During this clash, Zafar defiantly proclaims that Roop's heart belongs to him, igniting further conflict.
Amidst rising chaos, Roop finds herself torn between the two men. She ultimately consummates her marriage with Dev, despite her feelings for Zafar. Heartbroken, Zafar sends her away as he witnesses the dangerous escalation of tension around them. In a desperate attempt to flee to Amritsar, they face violence firsthand when the compassionate maid Saroj (Achint Kaur) falls victim to a brutal attack.
As riots grip Lahore, Zafar's confessions strike a chord with Roop, leading them to confront their true feelings for one another. They brave the chaos to save Dev from a mob, but the tragic turn of events culminates in Zafar's murder at the hands of Abdul as Roop and Dev fight for their escape.
A decade later, Roop and Dev find themselves in a joyless marriage, haunted by memories of the past. They recount their harrowing experiences to Aditya (Pavail Gulati), a journalist dedicated to documenting the partition, indicating that their story is far from over, even as time has forced them apart.
