Child artiste is the star of this edge-of-the-seat thriller

Director Viknesh's 'O2 (Oxygen)' is a nicely made, engaging thriller that keeps you hooked from start to finish. The story starts off in an unassuming fashion but soon turns into an intense thriller, thanks to a well-thought-out plot.

Parvathy (Nayanthara) is a single mother whose life revolves around her eight-year-old son Veera (played by child artiste Rithvik), who suffers from a chronic lung disorder. As a result, the child cannot survive without an oxygen cylinder.

Parvathy gets to know that a surgery could help her child recover from the disorder and lead a normal life. So, she chooses to take Veera to a hospital in Kochi, where such a surgery has been arranged for him.

Mother and son board a private bus to Kochi. The other passengers in the bus include a politician who is out of power and his assistant, a father who is disillusioned with his daughter as she is in love with a young man from another community, the girl's lover who is a student of medicine, a convict who has just been released from prison and a corrupt policeman who is off to Kochi for an illegal deal that is bound to make him super rich.

The bus sets off on a stormy night to Kerala. What happens during the journey is what 'O2' is all about.

The film has some fantastic performances to offer. Interestingly, the best performance does not come from Nayanthara but from child artiste Rithvik, who does a stellar job of playing Veera.

Joyful when he is with his mother, scared when she becomes unconscious, brave when he offers to step up for a task that could make the lives of the other passengers so much better, cute when he does an altruistic deed to save people, Rithvik is just adorable and steals your heart.

'Aadukalam' Murugadoss, who plays the God-fearing, conscientious driver, is a delight to watch as well. His performance in the scene in which he chooses to stick to doing what is right, disregarding life-saving benefits that some people have to offer, is just brilliant.

Nayanthara, who plays Parvathy, comes up with a neat performance. Equally good is RNR Manohar, who plays the politician no longer in power.

Bharath Neelakandan as the police officer Karunai Rajan looks truly menacing.

He looks the part and is able to induce an element of fear in the hearts of audiences with absolute ease. Bharath's impressive acting skills combined with Vishal Chandrashekar's apt background score enable director Viknesh to strike terror in the hearts of audiences. Tamizh Azhagan's aerial shots are a treat to watch.

On the flip side, the film has a climax that is not very convincing and that comes across as a big letdown. Otherwise, 'O2' is a neat family entertainer that is definitely worth a watch.