Between the campaign and the Tamil capital...
By means of his Indian coracle, Saravanan (MGR), a big-hearted boatman assures small connections and makes in this way his living.
His younger sister Sivagami (C. R. Vijayakumari) in fact so much. That's the way it goes, with Parvathi Ammal (S. N. Lakshmi), their mother, that they love.
When Saravanan has to gather endows her with Sivagami, he leaves his province for the neighbouring town.
During his absence, a film unit, under the leadership of spirited one director Muthu (R. Muthuraman) (come for locations) seduces Sivagami and rejected then without arousing her suspicions, by getting back to the capital.
Parvathi Ammal discovers the pregnancy of her daughter Sivagami who wants at all costs to wash her dishonor.
She leaves for Madras to find Muthu. She meets accidentally on Vaalee (Jayalalitha) who is to be the beloved of Saravanan and become friendly (Both young ladies, on the other hand, do not know that they are a sister-in-law due to Saravanan).
Vaalee, when to her, a saleswoman of lassi, with the well dipped character, had to resolve to avoid the ceaseless and more and more indecent harassings of her maternal uncle Somu (S. A. Ashokan), a gallows bird, by coming to hide in the big city.
This last one also moves into the metropolis.
Informed the lot of his younger sister, Saravanan sees his mother succumbing in the confusion.
The older brother decides in his turn to join Sivagami and to look for the man who is at the origin of all their misfortunes : Muthu !
The casting is established according to the original order of the credits of opening of the movie, except those not mentioned
Thaer Thiruvizha was shot in sixteen days. M. G. Ramachandran, besides playing the lead role of the boatman Saravanan, also made a cameo appearance as his real self presiding over a play.
The music composed by K. V. Mahadevan.