In Anna Nagar a single day unravels a tense, inwardly driven drama where possessiveness and hidden loyalties push ordinary lives toward a bruising edge. Prasath [Bharat Raj] runs a small-time pimping operation with his partner Chetta, but he shows an unusual, almost protective care for a client named Buvana [Riythvika], treating her better than the others in the group.
One night, a client named Santosh seeks a girl, and Chetta suggests Nirmala alias Nimmi [Meera Nair], a woman who keeps her profession a secret from her worried family. She is driven to go through the night’s work by necessity, and she is dropped off at Santosh’s place by Subramani [Mayilsamy], a cab driver who becomes a quiet ally in the confusion that follows.
The next day, Prasath and Chetta discover that Nimmi has not moved on to other clients and that Santosh claims she left, his phone unanswered. Their search, aided by Subramani, leads them to Santhosh’s house, where Santosh lies dead and Nimmi is nowhere to be found. The investigation meanders to KFC and back to Santosh’s home, leaving them with more questions than answers. Eventually, they return to the scene and discover Nimmi dead. Prasath is left morally unsettled as Chetta is caught up in the fallout, and a moment on a rooftop reveals a startling truth.
The man who steps forward is Mathivanan [Kathir], an NRI who visits India each year to see Santosh. In a tense, night-time sequence, Santosh invites Nimmi to a sexual encounter, and Nimmi engages with Mathi. The encounter spirals when Mathi, who is revealed to be a transgender person, asks Nimmi to leave, only for Nimmi to stay defiant. An accidental killing follows: Nimmi dies, and Mathi confesses, revealing his transgender identity and the wish for Santosh to share his own feelings. He hides Nimmi’s body in the fridge and tells a recovered Santosh that she had left earlier.
Santosh soon uncovers Nimmi’s body and confronts Mathi with the truth about his identity. In a moment of cruelty and fear, Santosh is killed by Mathi, whose emotions and sense of isolation intensify the confrontation. The confession and the killings unfold in stark, painful honesty, with Mathi’s pain and guilt looming large.
Months pass. Chetta tightens control over his girls, while Prasath, spurred by Subramani’s words, renounces the pimping life and marries Buvana. Mathi begins to live openly as a transgender person, choosing to grow his hair long and pursue a new life beyond the shadows of the night. The film closes with a tentative, hopeful note, showing a few transgender people and signaling a world that continues beyond the events of that fateful day.
