Plot
In 1964, under the glow of a supermoon on a rainy night, three people—Ganesh and Lalitha, a couple who have eloped to marry and their friend, Manohar—travel together by car. Manohar appears to support their union, but in reality, he harbors sinister intentions and is secretly in love with Lalitha. Along the way, they encounter a mud-stuck cart, blocking their path carrying a heavy angel statue, far too heavy for a single person to move. After maneuvering past it, they reach Manohar's beach house and settle in for the night. Later, Manohar gets drunk and gets his pistol from his car. As he tries to creep toward the couple's room from his car, intending to kill them, he witnesses the lights in his beach house and the street flickering. But before he can act, an impulsive noise startles him, and he walks toward the street, away from his beach house. A gunshot rings out from the house, and when he bursts into the room where his friends are sleeping, he finds them dead. Horrified, he tries asking a barely alive Ganesh about the killer, only to realize the terrifying truth of who it is.
60 years later, in the present day, Vasanth and Aaranya, a married couple often at odds, try to navigate their relationship's rocky terrain. One night at a pub, Vasanth gets into a fight, leaving Aaranya deeply disappointed. To make amends, he proposes a vacation but Aaranya suggests a weekend trip to their new apartment in a quiet township. As they drive, they pass a statue from 1964 prominently erected along their route. Being the first residents in the apartment complex, they are alone for that night and they intend to stay with a single security guard on duty. According to the township promoters, the angel statue, rooted since 1964, remains in place due to a history of mysterious events thwarting relocation attempts, leading the church to deem it divinely intended to stay. They buy some supplies from a nearby store and settle in for the night. Their first abnormal encounters are mysterious painting gifted by a mysterious person and the absence of a security guard to open the main gateway. Vasanth and Aaranya retire for the day and when start to make love, the power goes off and the same impulse noise sounds again. With no one to switch on the power backup, they go to the parking area alone to turn it on. Aaranya sees some stranger in the nick of time but she cannot see anyone. She is however sure that someone is there. The events startle them further with the ringing of the doorbell. To their surprise, it is Vasanth's friend, annoyed at what he says is a late-night call from them about some issue. Vasanth and Aaranya, who have made no such call, are baffled but bid him goodbye saying that they have no problems.
Later, Aaranya notices lights in the opposite apartment, surprising her since they were told they were the only occupants in the entire township. Then, strange occurrences begin to unfold. They spot a mirror image of their apartment across from theirs, complete with identical furniture, drinks, and decor. Alarmed, they watch as a curtain in their apartment suddenly catches fire; yet, once they put it out, it looks as if nothing happened. They receive a mysterious painting from an anonymous sender, only for it to shatter on its own and then reappear whole. Panicked, Aaranya calls friends and emergency services for help. Vasanth, hoping to communicate with the neighbors across, throws a note through the door only to have it returned to their apartment. Suddenly, an intruder breaks in and attacks Vasanth; it is another version of himself. Vasanth wrestles with this doppelgänger until Aaranya intervenes, driving the attacking Vasanth away.
Gradually, Vasanth realizes that these strange events occur whenever they cross a pitch-black area between the two apartments. Though he does not fully understand it, he senses that this darkness is key to their troubles. Each time they pass through it, they shift to a different timeline. In one timeline, they observe themselves calling their friend for help in one timeline but the friend arrives in another timeline before they make the call. In one timeline, the curtains catch fire and they extinguish them and in another timeline, the curtain remains intact. In one timeline, they had put off all the candles once the power backup was turned on but in another timeline, all those candles are in lit state. Determined to figure it out, Vasanth and Aaranya cross the darkness again. This time, both Vasanth and Aaranya see Vasanth in a secretive conversation with Aaranya's friend, discussing some incident at the pub sounding like something happened between them and they should forget about it and about the mysterious painting, which, Aaranya realizes, was sent as a gift from her friend. Misinterpreting this conversation, she suspects an affair between Vasanth and her friend. Vasanth tries to explain that her friend was the one who has made unwanted advances towards him, but Aaranya, unconvinced, storms off across the darkness alone. Vasanth chases after her, only to realize he is too late and she has entered a different timeline.
Now alone, Vasanth is detained by the police, who have arrived in response to Aaranya's distress call. Unable to explain her sudden disappearance, he escapes custody, attacks the officers, and returns to the township. En route, he spots an old car, and a strange instinct drives him to follow it. The car leads him to the home of Manohar, now an elderly man. Manohar reveals the secret behind the strange events: the pitch-black area is a wormhole connecting parallel timelines, activated by the supermoon. He arrived at the same place upon hearing the impulsive noise again, the township is the place where his beach house previously was and he lost it in a property dispute, thereafter understanding that the wormhole has opened once again. The same wormhole had opened on that fateful night in 1964, allowing him to witness his alternate-self murdering Ganesh and Lalitha. He theorizes that Vasanth and Aaranya's parallel versions might continue to meet them across timelines, even though each person can only exist in one timeline at a time and that is their reality. Manohar warns Vasanth that he must either reunite with Aaranya before the supermoon fades or eliminate his parallel self to secure his place in the reality he is in now.
With renewed determination, Vasanth returns to the township, crossing the darkness over and over, searching for the timeline in which Aaranya is still angry but unreachable. Exhausted and nearly defeated, he finally encounters a police patrol, just as Aaranya arrives with a friend. Relieved, Vasanth embraces her, certain he has found the right timeline and is reunited with his wife. As they drive home, Aaranya expresses concern over his prolonged absence since the power went off and he left to switch the power backup. Shocked, Vasanth realizes she is not aware of the night's strange occurrences and he is not in his intended timeline implying that he has lost the original Aaranya forever and that yet another parallel version of himself might still be active in this reality.
Moments later, Vasanth excuses himself to use the restroom at a gas station. He suddenly comes across his alternate-self standing behind him in one of the stalls. He joins Aaranya back in their car, with a mysterious smile on his face, leaving the audience to question: which version of Vasanth has truly returned to her?
