In the town of Chanderi, there is a widespread belief in the spirit of an angry woman known as Stree. During a four-day religious festival each year, she is said to stalk the men of the town, whispering their names and causing disappearances if they look back at her. To protect themselves, residents write "o stree kal aana" in blood on their doorways. Additionally, men are advised to avoid going out alone after 10 PM during the festival and to move in groups for safety. This practice reflects a societal parallel to the precautions typically advised to women for their own protection.
Vicky, a ladies' tailor in Chanderi, encounters a mysterious girl, credited as Girl with No Name, during the annual pooja season and falls in love with her at first sight. She requests him to stitch a lehanga. However, her frequent disappearances and unusual shopping list—containing items like a lizard's tail, white cat's fur, Datura flowers, meat, and brandy—raise concerns for his friend Bittu, who suspects she might be Stree. This suspicion deepens after another friend, Janna, is kidnapped by Stree. Vicky also grows wary of the girl and confronts her, but she vanishes yet again.
Vicky, Bittu and Rudra Bhaiya, the town's librarian and a paranologist, seek a way to save their friend Janna. They discover a partially torn book titled Chanderi Puran in Rudra's library, which details Stree's story and mentions an old fort. Vicky recognizes the fort from a date with the Girl with No Name. The trio visits the fort, believed to be Stree's lair, to find Janna. Stree drives away Bittu and Rudra and nearly attacks Vicky but refrains upon sensing love and respect in his eyes. She is then repelled by the girl's spell.
Later, the Girl with No Name reveals that she has been trying to defeat Stree for three years after losing someone close to her, explaining her presence during the festival. This confirms that she and Stree are different beings. That same night, Stree releases Janna at Vicky's request, but Vicky begins experiencing sporadic violent episodes. More men go missing when a possessed Janna, under Stree's influence, erases the word "tomorrow" from the protective phrases outside homes, leaving only "o stree come", effectively inviting Stree.
Vicky, Bittu, Rudra and the Girl with No Name decide to consult the book's author, Shastri, for a permanent solution to save the town. Shastri reveals that Stree was once an exceptionally beautiful courtesan desired by all the men in town. She eventually found true love and was set to marry, but on their wedding night, both she and her husband were killed by jealous townsmen. Since then, her spirit has sought her true love and aims to abduct every man in the town for revenge.
Shastri mentions a prophecy about a savior, and Vicky appears to fit the description. However, when he remembers that the savior is the son of a courtesan, his friends reveal that he is indeed a courtesan's son, which angers him, and he leaves in frustration. In a drunken state, Vicky confronts his father, who silently acknowledges this, deepening Vicky's turmoil. Eventually, Vicky feels grateful for his father's affection and resolves to save the town that has accepted him. The group devises a plan to kill Stree, but Vicky hesitates upon realizing she only seeks love and respect. The Girl with No Name suggests cutting Stree's long braid, the source of her power. Vicky follows through, and Stree vanishes.
The next day, the girl leaves the town, and Vicky bids her farewell, forgetting to ask her name. On the bus, she merges Stree's braid with her own hair before vanishing, implying that she is the witch seeking Stree's power. The following year, Stree returns to Chanderi and discovers a statue of herself at the town entrance, accompanied by a new phrase: "o stree protect us". This display of respect leads her to refrain from entering the town.