Duraipandi and Arunachalam have a history but Dhanam, Duraipandi's sister, wants her son Nalan to marry Nandhini, Arunachalam's daughter. However, the enmity between the two men worsens. Meanwhile, Nalan and Nandhini, who have grown having feelings for each other get married. The two families refuse to accept them and the newlyweds relocate to Chennai. Can they make it big in the city? Will they bring their two families together?

With a debut work, we expect some amount of freshness, be it in the idea or in presentation. But for his first film, Venkatesan takes up plots that Tamil audiences are very much used to. The film is split into two segments, with the interval being the median. In the first half, we are introduced to the characters in Duraipandi and Arunachalam's household and through the title song, the director establishes the characteristics and equations between these characters. But rather than dive straight into the story, Venkatesan gives us almost an hour of needless padding in the form of listless comedy by Soori and Rinson. There is romance as well, but a very much watered down new-age rural romance.

Thankfully, something happens at last when Duraipandi and Arunachalam have a public fallout and the director cranks up the tension by getting Nalan and Nandhini married. And, only then, Venkatesan reveals his true intentions — the film is not really about the two older men but about Nalanum Nandhiniyum! The second half, set in Chennai, turns into a wish fulfillment fantasy — the story of a couple who struggle for a bit in the city before striking it rich. The film is content to coast on feel good moments and melodrama bordering on implausibility. Nalan is a carefree young man and the onus of running the family falls on Nandhini, who takes up the job of a teacher. He whiles away the time while she works but once she becomes pregnant, he discovers responsibility just like that! And, what better place can make your problems vanish overnight than the film industry? So, we get a sub-plot about Nalan trying (and of course, succeeding) to become a director. This also provides the director to pay his respects to his guru — Venkat Prabhu.

Nalanum Nandhiniyum isn't a bad film per se but it is definitely an indifferent one. If the first half suffers from the serial-like treatment, you could dub the second half portions as Vikraman lite (Nalan even narrates a story about four friends, Vikraman's familiar trope, to a director). At times, the film seems to be somewhat autobiographical and given that first-time filmmakers often tend to put incidents from their lives into their films, you cannot discount the notion. What lets the film down, apart from the simplistic writing (Nandhini, for example, isn't really bothered that Nalan is living off her), is that there are hardly any challenges and even when there is sign of a likely struggle (like, when both Nalan and Nandhini are jobless after her pregnancy), it is brushed away with easy resolutions.