Thenali Soman(Kamalhassan) is a man who is scared of everything - a carryover from his life in Ceylon. He is a patient of Dr.Panjabootham('Delhi' Ganesh), a psychiatrist whose only aim is to smear the reputation of Dr.Kailash(Jayaram), a fellow psychiatrist but much more popular. So Dr.Panjabootham foists Thenali on Dr.Kailash, who is on a vacation alongwith his wife Jalaja(Devayani) and two children. Thenali endears himself to the family and falls in love with Kailash's sister Janaki(Jyothika). Kailash tries to get rid of him but his plans backfire as Thenali sees them as part of his treatment that is being effective in curing him.

An appreciable aspect of Thenali is that it is not a theme that can immediately be branded as a lightweight comedy. Unlike most other comedies which are nothing more than a collection of skits(more often than not based on mistaken identities), Thenali, with its story of a scared man and his psychiatrist, could have gone either way - as a comedy or as a serious movie. In fact there are a couple of scenes, where Kamal relates his past, that wouldn't be out of place in a serious movie. It is the screenplay that successfully turns it into a comedy. It is a relief to see the filmmakers squeeze laughs out of situations other than people switching places and some thought has definitely gone into the sequences where Jayaram's attempts to get rid of Kamal turn out to be treatment for him.

The movie has no pretensions about the kind of comedy it attempts. The script is peppered with distinctive 'Crazy' Mohan 'kadi' jokes and wordplays. These are jokes that make you laugh heartily at the moment but you struggle to remember after leaving the theater. I'll take those any day over jokes that are unfunny and the only thing you remember about them later are how painful they were. The rest of the comedy is predominantly physical with Kamal and KSR prepared to go to any lengths to get laughs. Barring a disgusting series of jokes involving Madan Bob vomiting, most other jokes are funny and work at their level.

Kamal's comic flair has been on display numerous times before and Jayaram, who also exhibits tremendous comic ability, joins him for the best scenes in the movie. Kamal is all charm as he wins the affections of everyone in Jayaram's family(with special attention to Jyothika, ofcourse!) and Jayaram's apparent irritation at this is cute and funny. Some of the scenes, like Jayaram's perception of what Kamal and Devayani are doing under the table(because of his own earlier idea for privacy) and morphing of scenes from older movies to earlier happenings, are quite clever. There is also a piece of dialog where Kamal attacks the put-on accent of tamil TV announcers that is right on target.

Unlike Kaadhalaa Kaadhalaa , Kamal's last foray into comedy, Thenali has a few oppurtunities where we see Kamal the actor and not just Kamal the comedian. His Ceylon accent is flawless and his narrations of his past, both to Jayaram and to the interviewer, are touching. Ofcourse the comedy offers him no challenges and he breezes through the rest of the movie. Jayaram, with a terrific comic performance, is the movie's big surprise though. His transformation from a dignified psychiatrist to a raving maniac is hilarious with funny facial contortions and excellent timing and dialog delivery. The rest of the cast is barely seen. Jyothika would be completely forgotten if not for the song sequences. Devayani doesn't fare much better. The ever-reliable 'Delhi' Ganesh and Ramesh Khanna raise several laughs. Rehman comes up with probably the weakest soundtrack in his career so far and this fact is only compounded by KSR's poor, unimaginative picturisation of the songs.