Professor Narendran(Nasser), along with his assistant(Swarnamalya), discovers that Earth is in danger since the moon(or some island in the Andaman islands that has the same soil composition as the moon. It is never clear!) is exploding. But he doesn't want to inform the people of the same since that will create panic. Meanwhile they also come across a cult, the members of which call themselves Agorars, that wants to cleanse the planet by killing huge numbers of people. A group of students, led by Rishi(Richard), joins Narendran as they try to stop the Agorars.

Director 'Yaar' Kannan earns some brownie points right away as we realize that the film has sci-fi intentions. Since most movies are unwilling to take risks and simply tackle variations of the same subject, any movie that goes against the tide by tackling a new subject is welcome. But the goodwill the director earns is dissipated soon enough once we see how he handles the subject he has chosen. We realize soon enough(to be more specific, when Nasser spots a comet from his own telescope and decides not to tell the world) that Yugaa is going to be an an extremely amateurish endeavor.

But even that realization doesn't prepare us for what comes down the line as even the movie doesn't seem be sure about the kind of movie it wants to be. We're initially led to believe that it is going to be a disaster film as the characters talk about the comet and other catastrophes. Suddenly, the topic is left hanging as the movie veers off into horror movie territory with the introduction of the cult with both suicidal and murderous tendencies. After this we start getting suicides and mass killings and unsatisfied spirits with bad intentions. Again, this is a new territory for Tamil films and wouldn't be so bad if everything wasn't so shabbily executed. The concepts, the picturization and the special effects(even for something as simple as a person leaping to his death) are all so bad that we're laughing rather than getting scared or even being intrigued.

As if all this were not enough, the movie routinely breaks for completely unconnected item numbers. While the director has been brave enough to make a film without a romantic track, he has felt the need to include songs. So we get all these item numbers that pop up out of the blue and do nothing to further the story. But one of the few things the movie does do right is the climax, which it keeps low-key. Instead of a special-effects-filled attempt (that would have looked ridiculous, going by the effects in earlier parts of the movie), the climax relies more on the brainwork of the characters and works better.

Nasser gamely tries to steer the movie along. He has a tough job, having to utter all the inane theories and explanations with a straight face. Going by the way she looks, Swarnamalya appears to be trying to fill Manthra's shoes. She looks lost most of the time. Richard erases any gains his career made with Naalai while Manikandan seems to be hellbent on acting only in the worst movies of the year. Only Stephen makes an impression, getting a chance to act(and doing a good job of it) in the scene where he is chased by the Agorars.