"Mr Mehta & Mrs Singh is the love story of two people who aren't married to each other," says music composer-turned director Vishal Bharadwaj about his new and by far most ambitious film.

While Aamir Khan was finalised as Mr Mehta a few months ago, the casting of Kareena Kapoor Mrs Singh comes as a surprise.

"Kareena Kapoor is an actress I've been watching since Refugee. Her performance in Mani Ratnam's Yuva finally convinced me of her extraordinary talent," says Vishal.

"After working with Shabana Azmi in Makdee and Tabu in Maqbool, I'm spoilt. I only want to work with the best actresses in the country. And you have to agree, Kareena is among our best today."

The director met Kareena at Aamir's residence. "They have never worked together before, and I wanted to see how they look together. I was pleasantly surprised to see that they shared great chemistry. They even read out some scenes together," says Vishal.

Before the makers zeroed in on Kareena, Rani Mukerji, Preity Zinta and Vidya Balan were considered for this role.

"But their dates were not matching Aamir's dates. So I had to look elsewhere.As for Vidya, she agreed, but I wasn't too sure about going ahead with her. But I'm glad Kareena is in the project. Aamir has worked with Rani and Preity before but not with Kareena. This is a completely untried pairing. That adds a special edge to the on-screen romance," admits the director.

Vishal seems unfazed by the drop in Aamir's equity after Mangal Pandey. "I don't think Mangal Pandey has affected Aamir's market in any way. It did stupendous business the world over. I wanted to work with Aamir for a long time. In fact, I believe some of our stars are immensely talented. Why should we hold their stardom against them?" asks Vishal.

Justifying Kareena's choice, he says, "I feel Kareena is a great performer. The fresh pairing will arouse a great degree of interest. Aamir too had a say in Kareena's inclusion. After all, he is the hero of the film."

UTV and Bharadwaj are trying to rope in the foreign technician who designed Russell Crowe's look in A Beautiful Mind.

"It's going to be a great role for Kareena — more often than not, we have seen her in the usual, heroine-type roles. Like Aamir, she too will age in the film and will have five different looks. Aamir starts off as a chartered accountant in the film, but undergoes changes over time; Kareena starts off as a housewife. I want the technician to style the look for Kareena and Aamir," explains the director.

There is one more main character to be added in the film, which will be selected from the Tamil film industry, as the script demands it. The entire film will be shot in Pondicherry.

Written by Vishal, Robin Bhatt and Abhishek Choubey, Mr Mehta and Mrs Singh starts shooting in June 2006. It will be produced by UTV.