The best way to watch Thodari is to consider it as a spoof thriller. Prabu Solomon seems to have taken a leaf out of Radha Mohan's Payanam for this film, which feels novel because of its setting — a train. There's isn't a properly focused plot as such (at least until the interval) and the film chugs along like a series of incidents that happen inside a train that is en route from New Delhi to Chennai.
A motley bunch of characters are travelling on the train. We have the pantry team headed by Chandrakanth (Thambi Ramaiah) of which Poochiyappan (Dhanush) is a part. Poochi's love interest Saroja (Keerthy Suresh, whose 'loosu ponnu' role is used to provide humour) is the touch-up girl of an actress who is also on the train. A central minister (Radha Ravi) is also among the passengers. His NSG commando (Harish Uthaman) has temper issues, and Poochi and Saroja become his target. The pacing in these portions is quite slow — more passenger train than superfast express — but the comedy sequences featuring Dhanush and Thambi Ramaiah are amusing, and help us look over this fact.
It is only closer to the interval that some semblance of plot emerges, when the train's driver dies inside his cabin and the train starts picking up speed (the film, too, picks up pace). Even as the plot begins to feel like a comic version of Tony Scott's Unstoppable (though, the director tries to counter this with a dialogue: Idea kudukka ellaam Hollywood padam paakanum-nu avasiyam illa), the scenes begins to resemble a satire, with media sensationalism, and the opportunism of politicians being the prime targets.
In his previous film, Kayal, Prabu Solomon exploited a disaster like the 2004 tsunami to shore up a romantic tale. In Thodari, he exploits the romance between his leads to mount a near-disaster. He alternates between comic and mock-serious tones and that helps us overlook the tackily staged romantic and thriller portions. The almost two-dozen supporting actors (from Radha Ravi, Karunakaran and Darbuka Siva to A Venkatesh and Chinni Jayanth) help keep us from getting bored while Dhanush, who is used more for his star value, is in fine B-movie form, gamely providing comedy, romance and heroism.