Suseendran's debut film Vennila Kabaddi Kuzhu was a refreshingly original and funny sports film with interesting characters and an engrossing screenplay. With a star - even if only a rising one - as hero, Suseendran refrains from attempting anything original in the story in his follow-up Naan Mahaan Alla. But the strong characters and fast screenplay are still there and they help overlook the lack of originality, ensuring that the director doesn't fall prey to the dreaded sophomore jinx.

Jeeva(Karthi) is a fun-loving youngster who has about 6 months to go before he gets his job posting and so has a lot of free time on his hands. He falls for Priya(Kajal Agarwal) when he sees her at a friend's wedding and it isn't long before she falls for his charms. Meanwhile, a gang of four college guys murders a young couple and disposes off the bodies by chopping them up. Jeeva sees the police gathering evidence by the side of the road and is angered but he doesn't know that the crime will have much bigger repercussions on his life soon.

Contrary to the title, Karthi is pretty much a mahaan initially. He is a good son who is never scolded by his parents, he woos Kajal with effortless charm, he is the darling of his entire neighborhood, he is instantly liked by kids everywhere and he is so kind-hearted that he ends up helping families he is supposed to collect debts from. Hell, he is even able to transform a curmudgeonly mother-in-law into a fun, dancing lady via a song! But the middle-class setting and the undertone of humor help avoid Karthi's characterization from looking like the superhero build-up that our heroes usually get and manage to keep the film grounded.

Karthi's straightforward nature - with both Kajal and her dad - make the romance work. He seems a tad overconfident at times but stops short of seeming chauvinistic. But more engaging are the scenes with his family. The usual strict father-affectionate mother situation is reversed without going to the other extreme and their conversations showcase a close-knit, affectionate family in a natural, underplayed way. His experiences at his new job also have their share of laughs, especially the way his job searching efforts intrude into his potential employer's personal life.

The bad guys are casually, chillingly evil from the first time we see them and their lifestyle and activities work well as a stark contrast to Karthi's down-to-earth life. We know that the two tracks will intersect at some point and considering the boys' nature and the presence of Karthi's younger sister, its nice that the intersection doesn't happen exactly as we think.

The route the film takes after this is also a surprise but the surprise is not quite as good. While Karthi's emotions and response are understandable, the film abandons the sense of realism it had built up so far in order to let him act on those emotions. From an ordinary middle-class boy, he almost turns into the character he played in Paiyaa and while the stunts are more realistic, it doesn't make it any easier to digest his transformation as he single-handedly takes on the villains and deals with them with more success than people who have been doing it for their entire life.

Karthi puts his natural charm to good use and is a big reason why his "too good to be true" character works without getting on our nerves. He seems comfortable in the action sequences too and conveys the intensity of his feelings. Kajal Agarwal hams it up sometimes during the romance but disappears completely once Karthik embarks on his mission. The actors playing the villains are terrific and the nonchalant way in which they go about their acts makes them truly scary. Jayaprakash, who seems to be quite ubiquitous these days, is impressive, especially during the scene where he advices Kajal. Yuvan sings Iragai Pole..., the best number in the album, and it is picturized well too as it plays in the background. Vaa Vaa Nilava... works better onscreen as the jolly atmosphere at the wedding makes it quite fun.