Kavya, a college student hailing from a wealthy family in the small town of Ambala, resorts to stealing and selling diesel from trucks to fund her pocket money, as her father refuses to provide for her expenses. Enter Humpty Sharma, a laid-back college guy in Delhi who idolizes Dilwale Dulhania Le Jayenge, skews his academic integrity through cheating, and attracts women effortlessly, yet has a heart of gold.
When Kavya, portrayed by Alia Bhatt, becomes engaged to an NRI doctor based in America, she decides to travel to Delhi in search of an extravagant designer bridal dress after her father, Ashutosh Rana, denies her request for the pricey item in Ambala. It is here that she encounters Humpty, Varun Dhawan, who immediately falls for her. Despite Humpty's advances, Kavya, initially indifferent, ends up establishing a friendship with him.
As luck would have it, Kavya is staying with her uncle, who happens to be the professor grading history papers at Humpty's college. Humpty had planned to bribe the professor after submitting a blank paper, but their fates intertwine when Kavya informs him that her uncle enjoys a drink or two and would probably be lenient in his evaluations. In a twist of fate, she requests ₹10,000 from Humpty, which he willingly provides to pass the course.
During their interactions, Kavya reveals her mission to procure an ethnic dress — a pursuit that mirrors her friend Gurpreet’s recent extravagant purchase. After discovering that Gurpreet was duped into buying a fake designer dress, she learns that Gurpreet had been blackmailed by an ex-boyfriend who recorded an intimate encounter. Driven by a sense of justice and adventure, Humpty hatches a plan to turn the tables on Gurpreet's ex, Bhanu, who is revealed to be a serial offender.
Humpty and his friends manage to infiltrate Bhanu's hotel room, setting up cameras to document his nefarious acts, including an encounter with a married professor's wife. They send the incriminating footage to both Bhanu and the professor's wife, resulting in a frenzy that nets Humpty some money, although Kavya is initially unhappy with the means by which it was obtained. However, throughout their escapades, Kavya gradually develops feelings for Humpty, culminating in a passionate night together before she returns to Ambala.
When Humpty's father and friends manage to contribute to the funds needed for Kavya's dress, she ultimately decides against buying it. Instead, she gifts Humpty a car, recognizing his father’s long-held dream. In a heartwarming turn, the group visits Ambala, where Humpty attempts to win Kavya's affection in earnest. Yet, Kavya's father, adhering to traditional values regarding arranged marriages, harshly disapproves of Humpty, even going so far as to physically confront him and his friends.
With pressure mounting, Kavya's father challenges Humpty to prove why his daughter should not marry Angad, her wealthy NRI fiancé, within a strict five-day deadline. Despite their exhaustive efforts, Humpty and his friends can't find any flaws in Angad's character.
On the day meant for her wedding, in a bold act of defiance, Kavya flees her home and calls upon Humpty to join her on the train. When their families converge at the station, her father’s rage culminates in him striking Humpty. During this tumultuous encounter, Humpty delivers an earnest declaration of love, explaining that while he may lack wealth or status, his feelings for Kavya are pure and profound.
In a pivotal moment, as Kavya dons her bridal attire, her father inquires if she has any lingering desire for the extravagant wedding dress. Her response, that she is not suited for elegance but rather for something more grounded, sparks a realization within him. He comes to understand that true fulfillment for Kavya lies with Humpty, the local boy she loves, rather than the affluent Angad. In a touching conclusion, he approaches Humpty and grants his blessing to marry his daughter.
