In Bombay of the 1980s, Albert returns home after seven years, greeted by his neighbor uncle, who informs him about his mother's recent passing. Due to Albert being unreachable, uncle had to organize the funeral without him. Uncle hands him over bottle of home-made wine prepared by him which he has named "Yadhoom". It's Christmas Eve and Albert goes to a bar/restaurant where he encounters a stranger who was meant to have a date with a beautiful woman named Maria. The stranger cancels it upon seeing Maria with her mute child, Annie, and requests Albert to tell her that he had to leave for some urgent work.
Albert, in turn, shares the situation with Maria and leaves the restaurant. By chance, he again meets Maria and Annie at a cinema, watching the film The Adventures Of Pinocchio, and they connect. Maria invites him to her apartment to celebrate Christmas Eve together. Albert introduces himself as an architect who has just returned from Dubai while Maria says she owns a bakery beneath her house. At her home, Albert hangs on her Christmas tree a "bird in a cage" ornament that he had purchased earlier that evening. While Maria plays loud music, she offers him whiskey and goes to put Annie to sleep. After that she returns to drink wine and they both dance together. As they bond, Maria reveals the difficulties in her marriage to Jerome who was initially her boyfriend's friend and has now become abusive. Albert talks about Rosie, his boss' wife whom he had fallen in love and eloped to Goa with seven years ago and who then had decided to go back to her husband but had passed away since. They then decide to go out for a walk and Maria writes a note for her husband who she says might come back anytime. They decide to show each other their favorite spots in the city and then Albert invites her to his apartment where his neighbor uncle sees them.
After some time, upon returning to Maria's apartment, they are shocked to find Jerome lying dead on the couch, with a gun in his hand and Maria starts crying. Maria suggests calling the police, but Albert says he does not want to be involved. He reveals that he was the one who had killed Rosie and had spent the last seven years in prison and had just been released that day. He says his presence could lead to unnecessary suspicion on both and leaves but before that he tries to wipe off all his fingerprints but is unable to find the toy bird cage. Shaken, Albert seeks solace with coffee at a stall nearby, but is surprised to see Maria walking down calmly with her child again. Intrigued, he follows Maria who goes to midnight mass at the church. There she pretends to faint and falls on Ronnie, a caterer. While Ronnie decides to take her to hospital, Albert intervenes to help him and he asks Albert to drive his car. Maria wakes up and asks them to take her to her house. Returning to Maria's apartment, Maria offers them drink and asks them to come up. Albert is surprised to find Jerome's body missing when they go inside. Maria plays music, offers drinks to them and goes away to put Annie to sleep while Ronnie reveals his intention to sleep with Maria. Albert notices that the toy bird cage is on the Christmas tree and is surprised since it was not there when he came the second time.
Maria asks Ronnie to drive her to the church to find her lost watch and writes a note to her husband who she says might come back anytime. Ronnie suggests to drop Albert off on the way to which he agrees. Albert suspects Maria since he had already seen an old lady giving Maria her watch that she had dropped while fainting in the church and she had put it in her purse while Ronnie was away getting the car. After dropping Albert off, Maria and Ronnie head to church. Albert however returns to Maria's home through a backdoor staircase and is shocked to discover Jerome's body in the exact same position when he had come the second time. He comforts Annie who is sleeping in her bedroom. He asks her not to get petrified and says he is "Santa". When Ronnie and Maria return, Albert hears Maria cry seeing the dead body and asking Ronnie to call the police who promptly does so. As Maria comes to see Annie in her room, she finds Albert there and asks him to leave. As Albert climbs down the backdoor stairs, he sees the police and in fear of being mistaken as a thief, he tries to go back to Maria's home through the backdoor but finds it locked from the inside. Hence, he proceeds to go to the upper floor where he is flabbergasted at what he sees. Meanwhile, Ronnie asks Maria to narrate all the events as they happened but they mutually decide not to mention anything about Albert as it would lead to unnecessary confusion. The police, suspicious of Ronnie, take him to the station after sealing the crime scene.
Soon after, Maria goes to the upper floor, but is surprised to see Albert there. Albert reveals to her that he has found out that Maria had created a replica of her apartment as an alibi in the upper floor where she had taken him the first time and again the third time when he had come with Ronnie whereas the dead body was in the lower floor and she had taken him there the second time and also the final time when she came with Ronnie - thereby creating a situation as though Jerome was dead while she was away with the stranger.
Maria breaks down and confesses to Albert that she killed Jerome as he was suspicious of her fidelity and abused her. She reveals how she spiked Jerome's drinks with his own drugs and killed him with his own gun in his own hand while loud music was playing upstairs when Albert came the first time. She also reveals how she used to bring Annie to the lower floor through the backdoor stairs to avoid suspicion. Albert offers to help her. They decide to destroy the replica apartment. While doing so they find Ronnie's wallet hidden in the couch but Albert holds on to it and decides to return it to "Lost & Found" section in the church the next day. He also asks Maria to give the toy bird cage to Annie as a gift from Santa and leaves for his apartment.
During the police interrogation, Ronnie reveals about Albert as proof for the events unfolded. Albert is brought to the police station the next day. There he reveals that he was on parole from Nashik Jail and that he had not revealed the fact to Ronnie, but he testifies Ronnie's statement as true. Maria's version also matches their statements. As the postmortem report reveals it to be suicide, the police decides to let go of all the three - Ronnie, Albert, and Maria - and close the case. However, Ronnie admits that he is ashamed to agree, but he had deliberately hidden his wallet in her couch so that he can come again to her home with the excuse of searching it, but it wasn't found the second time he came. Maria says she didn't find any wallet.
Thus, Ronnie puts forth a theory that a thief might have broken in and during his theft attempt, he might have killed Jerome and left with his wallet. Thus, it is deduced that whoever has the wallet might be the killer. Annie, playing with the toy bird cage which Albert had given, reveals to the police that it was given to her by her "Santa" and points her finger at Albert - thus negating the events as explained to the police. At this point, Albert shows Ronnie's wallet to the police and surrenders to them before which he puts an engagement ring on Maria's finger, implying that he will take the blame to save Maria.
