Gethu begins with Craig (Vikranth), a sniper, who is ordered to assassinate India's top scientist, Abdul Kamaal (if you did not get who the director is referencing here, here's another tip: he has written a book titled Agni Iragugal). The challenge for him is to draw Kamaal, who never gets out of his research facility, to make a public appearance. So, he comes to Kumily, a sleepy hill town, with a plan in mind. Meanwhile, in the town resides Sethu (Udhayanidhi), a librarian, and his father, Thulasi Raman (Sathyaraj), a PE teacher. The righteous Thulasi gets into trouble when he takes on Kandhan (Mime Gopi), the owner of a bar which has sprung up next to the school and even gets framed for his murder. With Kandhan's politician brother and gangster mother baying for his father's blood, Sethu must clear his father's name. What he doesn't realise, initially, is that his efforts will also save Kamaal.

Director Thirukumaran has the essentials for a high-concept thriller — a determined hitman, an ordinary man who stumbles into a nefarious plot by accident, a sub-plot that provides some mystery, and a bit of family drama. It is in his execution that he falters. For a thriller clocking in at under two hours, Gethu moves at a pace that is as sleepy as the hill station where the action happens. The director's choice of slow motion shots as a device to make the action stylish and prolong the tension in the plot works against the film. Add to that a silly romantic track — featuring Amy Jackson, who plays a book thief! (you just can't help rolling your eyes at the naivete) — which is made further unbearable with songs popping up every now and then halting the story's flow (perhaps the director felt that he had to give Amy and composer Harris Jayaraj something to do), and you have a film that can test your patience.

But, the film redeems itself a bit, chiefly due to M Sukumar's visuals, which turn Kumily into a place straight out of a travel brochure. We just cannot take our eyes of the screen because the frames are so irresistible. Udhayanidhi as the dutiful son also fits the part, but Vikranth, as the terrorist who hardly speaks, feels a bit of a lightweight (he looks too young to be considered a formidable foe). Then there is Sathyaraj (who is given the top billing in the credits), and the veteran chips in with a performance that makes us care about the fate of his character and his family. Thirukumaran doesn't this character as just another supporting character. When the character comes out of prison on bail, we get a scene with only Thulasi and his wife, and the director treats it with the right amount of emotional drama. It is a pity that he could not find this balance when it comes to the other scenes.