Manmadan Ambu  is a 2010 Indian Tamil-language romantic comedy film directed by K. S. Ravikumar. Written by Kamal Haasan, it stars himself alongside Trisha, Sangeetha and R. Madhavan, while featuring Oviya, Ramesh Aravind, Usha Uthup, Manju Pillai and Urvashi among others in supporting roles. The film music composed by Devi Sri Prasad, with several songs written and sung by Kamal Haasan himself .
It is another typical kamal’s family friendly movie contains a perfect mix of sense and nonsense with some beautiful emotional scenes, hilarious dialogues and some philosophy.

Here is the plot of movie...
Ambujakshi (Ambu) alias "Nisha", a film actress has a boyfriend Madhanagopal (Madhan), a wealthy entrepreneur. she is shooting for a film with actor Suriya, and Madhan and his mother Indira are suspicious of her relationship with the actor. While returning, he let Ambu drive his new car. Madhan advised Ambu to stop acting but she refused, leading to an argument that almost caused their car to crash into a smaller white car. Unable to bear any more arguments, Ambu takes break from her relationship with Madhan and walked away. After  three years she arrives in Europe to spend the vacations with her school friend Deepa, a divorcee, and her two children Viswanath alias Vish and Bhagirathi. While going in a taxi, Ambu recalls an early incident
Madhan now suspects that Ambu may be having a relationship with her colleagues in the film industry. To end that, he hires detective Major Raja Mannar (Man) to follow her when she goes on a cruise for a vacation in Barcelona. Mannar accepts, as he needs money to pay the hospital bills of his friend Rajan, who is diagnosed with cancer, and who is being taken care of by his wife Mallika. Contrary to Madhan's suspicions, Ambu is loyal and virtuous; when Mannar reports this, Madhan refuses to pay him as his suspicions were unfounded.
Disappointed, Mannar, to save his dying friend Rajan, fabricates a story and tells Madhan that she is having a secret affair during her trip. In the process, he introduces himself as a manager of a security company to Ambu, Deepa, and Deepa's children, and he becomes close to the group by spending time with Deepa’s children and saves Vish who swallows the coin. While getting closer to Ambu, Mannar says to Madhan that Ambu's intentions are good, but the man she was being seen with, is of poor character. Madhan does not like what he hears and eventually breaks up with Ambu. In the background, Madhan's mother Indira, who has never liked Ambu, tries to arrange her brother’s daughter Sunanda married to Madhan as agreed previously.
While recollecting his past as an Army officer to Ambu, Mannar reveals that he lost his wife Juliet three years ago in a car accident. Ambu realizes to her horror that the accident was caused by her during the argument with Madhan. Both of them decide to confront each other with the truth, but Ambu misidentifies Kunju Kurup as Madhan's detective, slaps him, and tells him that she loves Mannar. Meanwhile, Rajan undergoes an operation immediately after the chemotherapy, in an attempt to keep him alive. To make things worse, Madhan announces that he will visit them in person at Venice. Madhan confesses that he is real spy who Madhan appointed to Deepa to get her support for saving his friend Rajan. Ultimately, Mannar and Deepa stage a plan with the help of Kurup and his wife Manju to deceive Madhan for the final break-up with Ambu. But Mannar is not fully okay with plan of wrongly portraying Ambu.
Madhan arrives at the place and various mix-ups and misunderstandings take place among the characters. There are lot of laughs. Finally, drunken Madhan realises that Ambu has fallen in love with Mannar and accepts it with a heavy heart. During the drama Madhan  and Deepa catch feelings for eachother. So Madhan becomes okay about all the lies. Also At the same time, Rajan recovers from cancer. Mallika calls and tells Mannar this with tears and thanks him. The film ends as everyone returns to India on the cruise, with Madhan and Deepa starting a relationship and Mannar and Ambu proposing their love with voice over of Mannar and Ambu reading poem of how their life would be.

It is feel good movie with a lot of deep work done on script and drama. The chemistries between the casts are make the movie even movie admirable. It's so sad to see so less recognition to it. I Don't know why this film is not superhit, I wish this movie rerelease in theatre. It is one of my family’s favourite kamal film. We never miss the chance of watching it on tv.