Nakhanghal meaning 'nails' essentially dealt with an owner of a tea estate who believes in the ideals of a political party that fights for the rights of the workers, because she was a labourer-turned- estate owner which K.R Vijaya does in the film. The story follows the template of two murder cases. Saraswathi (K. R. Vijaya), an inmate of an orphanage who believes in the ideals of a political party that fights for the rights of the working class is married to Mathew, an estate owner. The story of the film starts five days after the brutal murder of Mathew. A young graduate, Sankarankutty (Madhu) is appointed by Saraswathi Mathew as the Manager of the estate following the death of her husband. The past life of the important characters is narrated by powerful dialogues, rather than in usual visual "flashbacks" . A young leader of the estate workers, Yesudas (Raghavan), an estate worker Muthappan (C. A. Balan) and Saraswathi Mathew are the prime suspects in the case. Later, Muthappan is also murdered. Police frame false charges against Saraswathi Mathew . The local police was twisting the murder case in favour of real culprits, the estate owners Ramunni Menon (Veeran), John Sebastian ( Paravoor Bharathan ) and their group who murdered Mathew by mixing poison in the coffee served to him through Mathew's servant Pankiyamma (T. R. Omana). They murdered Muthappan also who witnessed Mathew's murder. Sankarankutty succeeds in unfolding the mysteries behind the murder of Mathew and Muthappan and saves Saraswathi Mathew from the false charges. Sankarankutty's lover Gomathi (Jayabharathi) and Yesudas are children of the party worker Achuthan Nair (Sankaradi) who were brought up in their childhood by Saraswathi when they were admitted to the orphanage following the death of their mother. Later Gomathi was brought up by a party worker Pappunni (S. P. Pillai). Ramunni Menon and his group is arrested by the crime branch. The film ends with a message – the real owners of the estates are the "workers" who built up the estates with their hard work. Saraswathi Mathew hands over the estate to the Union of the workers and leaves to the orphanage from where she came. But the local bureaucratic estate owners who were against his" pro workers policy" murdered him.The success of the film is attributed to the scriptwriter Thoppil Bhasi and director A.Vincent. Some critics feel that the film was not as impressive as the novel.But the pacing was very fast and kept the viewer engaged.Like in Nadhi, where he stationed a major portion of the film in the river, here A.Vincent explores the beauty of the tea estates in Kerala. Madhu kept strolling through estates of Kerala in the song 'Krishnapakshakkili Chilachu' in his trademark swaying motion where he kept swinging his arms all through. It might appear kind off funny today but back then it was Madhu's patented dancing style which he continued for years to come. The scene immediately after the song was considerably bold by the 70s standards where Jayabharathi removes her sari to use it as a cord to pull Madhu up, when he slips down from the cliff.The love story in the film was refreshingly restrained and despite a love triangle, A.Vincent never loaded the proceedings with melodrama. The screenplay never makes a huge hue and cry of the scene when Jayabharathi rejects Madhu and yet remains his friend or subsequently when she gets back to Madhu and disowns Mohan. The director had a very matured and progressive outlook towards relationships.The film also deals with its title conflict of factory problems very smartly. Madhu's repentance for his misdeeds and the way he convinces his gang to give up the wrong path is very interestingly portrayed. The courtroom drama in the climax (where Madhu fights for K.R Vijaya) is thoughtfully conceptualized and very well-worded with a balanced and impartial point of view. It neither glorifies or glamourizes Shankarankutty's attitude nor does it ignores his remorse. Through factory problems outside tea estates of Kochi, the film captures the glory of good old tea estates of the city, some of which (like Kannan Devan) exist even today. A.Vincent also very intelligently incorporated the real-life Communist ideas in the initial reels of Nakhanghal thereby adding political width to the film . Years later I.V Shashi and P.G Vishwambaran replicated the same formula in their films Anghadi (1980) and Sphodanam (1981) respectively and to good effect.Like any Supriya production, even this film was blessed with melodious tunes by G.Devarajan. The soundtrack had everything from love songs to a bhajan to a Jayamalini cabaret number. 'Krishnapakshakkili Chilachu' and 'Gandharvvanagaranghal' are timeless tunes. Madhu was charming as always and gave a splendid performance in a character that had an interesting graph. K.R Vijaya looked beautiful and was natural as ever in her performance. K.P Ummar and Kaviyoor Ponnamma were good in their special appearances. Jayabharathi played a supporting part as Madhu's lover and was decent.