A friend in need, Shyam-the only son of wealthy widow, dashes to Girjapur to hold up the marriage proceeding of his friend Kesho with some ill-reputed girl and carries along Rs. 20000/- in cash for emergencies. Wily Benarsi Prasad's aids, Mala, Dulare and Jogi are after Shyam in the same train to steal away the cash from Shyam who, somehow, out tricks them all. On arrival at Girjapur, the trio bargains off their prospective victim Shyam to Bhairav Prasad, the elder brother of Benarsi Prasad. Bhairav manipulates fake marriage between Shyam and Koili, a girl kidnapped since childhood, and instructs Koili to knock out the cash for him. Young Koili is attracted towards Shyam and she helps him escape from the trap. Koili's loving memory averts Shyam's mission and Shyam, on reaching Kesho's house, helps through the proposed marriage of his friend with his ill-reputed fiancee. After the marriage ceremony Shyam returns to Koili's place under new disguise of Pathan and eludes away with Koili from Bhairav's fold, Benarsi, jilted lover Koili, approaches Shyam's mother and informs her of Shyam's act of Kidnapping. Misinformed mother disbelieves her son's story and turns out Koili from the house.
Externed and distressed Koili encounters a blind retired Captain, Benarsi Prasad in disguise, and innocently goes along to his house. Benarsi Prasad plans out an immediate marriage ceremony with Koili,andShyamagain appears on the spot in disguise of Pandit to perform the sacred rites, an takes away Koili for good, to his own house. This time under a new name Kaushalya, and introduces her as his friend's sister. The mother approves of Kaushalya as the girl for Shyam and gives her consent for their immediate marriage. Jilted Benarsi Prasad and his aids masqurades as Sadhus in front of Shyam's house-Shyam instructs Koili to remain shut and out of sight but mother plans to take around her would be daughter-in-law to city circus-The situations mounts to breath taking climax here, and Shyam is at his wit's end, as how to keep up his mother's illusion of Kaushalya.
For convincing happy ending you will have to see "Banarasi Thug" on the screen.
[from the official press booklet]