Spread across Mumbai, over a decade the film is about the relationship between the quirky, rebellious Meeta (Parineeti Chopra), and the mischievous Nikhil (Sidharth Malhotra) struggling with their respective families to fit in. Nikhil bumps into Meeta on the occasion of her sister Deeksha's wedding while Meeta is on the run. He falls in love with Meeta's sister Karishma on the same day.
The film jumps to the eve of Nikhil and Karishma's engagement. Karishma's wealthy father, Devesh Solanki, does not approve of Nikhil as he finds him to be a lackadaisical young man. On the day of his engagement, Nikhil promises Karishma that he will prove himself to be worthy of her within the next seven days.
Nikhil is re-introduced to Meeta by Karishma and is instructed to put her up in a hotel. Nikhil recognizes Meeta. In an attempt to please Karishma he decides to keep Meeta in the flat above his own house, with his crazy extended family. During the course of Meeta's stay at Nikhil's house, they come close to each other and open up to each other.
In the midst of this confusion, the truth of relationships is unfolded; the strength of unions is tested and love triumphs.
Parineeti Chopra as Meeta: Quirky and unpredictable, Meeta is a free-spirited girl, a misfit in her rich, traditional Gujarati family, despite the indulgence of her father Devesh. Extremely intelligent, she is a chemical engineer from IIT and doctorate from Zhejiang University in China. She sees life in a logical analytical manner and is not weighed down by emotional consideration or baggage. She is passionate about her work and is driven to meet her goal, even if she achieves it in her own eccentric way. Nikhil brings a balance to her life and releases her pent up emotions revealing her more humane side.
Sidharth Malhotra as Nikhil: Nikhil is an optimist willing to do anything to make things work, even if his heart is not in it. He is a free-wheeler, pressured to confirm to the expectations of those around him. Though mischievous, he is extremely righteous and is struggling to cope with the expectations of his fiance Karishma. Meeta helps Nikhil reclaim his life and frees him from the drudgery of living a life for others at the expense of his own happiness.
Adah Sharma as Karishma: She is most attractive of the sisters. She is a top T.V actress and frequently motivates Nikhil to achieve his goals. She is an extremely emotional person for whom self-respect, dignity and propriety are important.