Nalla Thanka is a landmark Malayalam film directed by P. V. Krishna Iyer, and produced by Kunchacko and K. V. Koshy. It was the second film produced at the Udaya Studios, the first being Vellinakshatram (1949). The film marked the debut of several artistes, including actors Augustine Joseph, Vaikom Mani, Miss Kumari, Miss Omana and S. P. Pillai, music director V. Dakshinamoorthy, and cinematographer P. K. Madhavan Nair. It was one of the first commercially successful Malayalam films.
Nallannan is the King of Madhurapuri. His sister Nalla Thanka is married to Somanathan, the King of neighbouring country Ratnapuri. Alankari, the wicked queen of Madhurapuri becomes jealous of the happy married life of Nalla Thanka. Years pass and one day, drought strikes Ratnapuri. Nalla Thanka and her seven children seeks refuge in Nallannan's palace. Nallannan promises all help while Alankari tortures Nalla Thanka. But Nalla Thanka hides the misdeeds of Alankari from her brother as she does not want their family life to be disturbed.