‘Lootera’ is an aristocrat's daughter falls in love with a visiting archaeologist, but he holds a secret that could drive them apart. It is inspired by O. Henry's ‘The Last Leaf’. Lootera is a love saga of yore. The plot is an amalgamation of a story written by Vikramaditya Motwane with O' Henry's short story, The Last Leaf. It begins in Manikpur, West Bengal, in 1953, a landlord goes to watch a Chhau dance with his daughter, Pakhi Roy Chaudhary (Sonakshi Sinha), an aspiring writer. After Pakhi has an asthma attack from the ensuing excitement, she is rushed home and given medication. As she recuperates, her father comforts her and narrates the story of the invincible king whose soul resided inside a parrot, telling her that she is the parrot within whom his life resides.
One day, while learning to drive a car, Pakhi accidentally bumps into a motorcycle and mildly injures a handsome youth. A few days later, the same youth introduces himself to the landlord as Varun Shrivastav (Ranveer Singh), an archaeologist who wants to study the land surrounding the temple that the landlord owns. Over the next few weeks, Varun charms the landlord and his daughter with his knowledge and persona, and is invited, along with his assistant, to live at their home.
Soon, love brews between Varun and Pakhi as they bond over art and literature, and their love culminates into a passionate affair. Meanwhile, an act passed by the Indian government debars the power of landlords, causing tension in the Chaudhary household. The ancient artefacts the family owns must be sold, and Varun helps arrange the purchases.
As Varun's stay comes to an end, he asks Pakhi's father for her hand in marriage, and preparations of their wedding begin. Before the wedding, Varun's uncle, who has raised him, arrives and discourages Varun from marriage, stating that Varun will only give Pakhi grief because of the danger of what he does for a living—people like them are not meant to fall in love and have normal lives. Varun is conflicted but agrees and makes his choice: he and his assistant flee that very night, along with all the valuables they stole from the landlord. On the wedding day, Varun is nowhere to be found, and it is discovered that the idols from the temple have been stolen and the currency notes from the purchase that Varun arranged of the family's artifacts are all counterfeit.
A year later, a sick Pakhi is living all alone in Dalhousie. Her father has died and she has still not recovered from her heartbreak. When a police inspector asks her in helping him nab Varun, she refuses to do so, wanting only to forget him. Soon after, Varun and his friend turn up at Dalhousie for their next heist and stay at a lodge on Pakhi's property. Things turn ugly when the police gets wind of their whereabouts and a chase ensues. After Varun accidentally kills his friend along with a constable, he seeks refuge in Pakhi's house.
Although Pakhi does not turn him over to the police, she is nevertheless enraged and repels Varun's comforting advances and explanation. In a letter, she explains to him that she is dying of tuberculosis and will die the day the last leaf falls from the wilting tree outside the window.
Varun plans his escape but refuses to go, and takes care of the ailing Pakhi instead. He confesses that he has regretted letting her go since the day he fled. Soon, Pakhi warms up to him and her faith remains intact when each day she finds one last leaf remaining on the tree.
Eventually, it is revealed that apart from taking care of Pakhi, Varun would also paint a leaf and tie it on a branch of the tree everyday so that she doesn't give up hope, it was his masterpiece. In the end, as he is about to escape, Varun is shot down by the police while Pakhi realises the truth after she looks at the painted leaf closely, and smiles with tears in her eyes.