Jaswinder "Jazz" Singh is a 40-year-old carefree womaniser who works in London as a property broker during the day with his brother Dimpy and parties at night in a bar owned by his friend Rocky, usually taking whichever girl agrees to go to his home for a one-night stand. Jazz and Dimpy have to negotiate a multi-million-pound deal involving a property in Hounslow, but his aged landlady Mallika Zaid refuses to part with her home because of an old tree, and his repeated attempts to convince her to give it up for the new construction do not succeed.
One night, Jazz is partying as usual when a girl spills her drink on him; she apologises and he carries on. The next night, at the bar, she reveals herself as Tia, a 21-year-old from Amsterdam who has come to London for personal work. He agrees to take her to his home. There, Jazz learns from her that he is one of three possible options for her father, based on a photograph of Tia's mother with him. When she tells him that she might be his daughter, he is aghast, but she advises him to take a DNA test to confirm the results. When the results arrive, it transpires that not only is Tia Jazz's daughter, but she also happens to be pregnant.
A shocked Jazz initially refuses to accept the truth; when Tia offers to stay with him and deliver her baby at his home, he refuses, saying that he cannot take on the responsibility of running a family. She moves in next door to his house. He consults his hairdresser friend Rhea, who is his age, for advice. She congratulates him and advises him to confront his being not only a father but also an impending grandfather. His reckless partying ways continue at personal expense, as once he falls from a bar table, drunk, and breaks his leg. His feelings for Rhea grow, but when he tries to make a sexual advance, she stops him and asks him to restrain himself from ruining their friendship.
Meanwhile, Tia visits Jazz at his home regularly, and silently resolves to endear herself to his family. One night Jazz's brother and their parents visit his home. Despite Jazz warning her against it, Tia embraces everyone, and catches them unawares when she shows them her sonogram on Jazz's projector, forcing him to explain the situation. Jazz realizes after a conversation with Dimpy that he actually should take care of Tia, and the father-daughter duo reconciles. They happily weather her pregnancy, until one day when Tia's hippie mother Ananya and Tia's boyfriend Rohan turn up from Amsterdam unannounced. Ananya and Rohan's carefree, drug-fuelled ways are too much for Jazz to handle, and he fears that this may impact Tia's delivery. Hurt by the final model of the construction in which the old tree is missing, she leaves; when Jazz confronts her, and attempts to convince her that the millions to be gained from the property will more than compensate for the lost tree, she tearfully tells him that he can't be her father, having not even an iota of emotion and attachment within himself.
A despondent Jazz ponders over whether the deal is really worth grieving an old lady, before he finally decides to call off the Hounslow project, even at the expense of money, to which Dimpy agrees. He then rushes to the Waterloo railway station where the three are waiting for their train; he proceeds to tell how he cancelled the deal and saved Mallika's tree, when Tia's water breaks suddenly.
The film ends with Rhea and Rocky joining the Singh family at Jazz's parents' home for Diwali celebrations. Kiara whispers into baby Kiara's ears that she will be the world's first baby to witness the wedding of both her parents and her grandfather, as Tia looks on happily.
