Anupam, in the news for his support of reformer Anna Hazare's crusade against corruption, plays two opposite characters in the children's superhero film directed by Satyajit Bhatkal and produced by Walt Disney studios. One is a negative character of an evil uncle and the other a positive role of that of a scientist called Magic for which he had to completely change his look.
"It is the most difficult thing I have ever done as an actor, because both the characters are two different people. They are not even brothers. There is no similarity between them.
"There were days when I was doing both the characters on the same day. So I used to first spend hours doing the make-up of one character, give the shots and then change the make-up and do the other character. And everything had to be different. I had to be conscious of body language, of gestures - every single thing was a practice. It was tiring at times, " Anupam told in an interview.
The 56-year-old actor had to spend five hours in one sitting to get his make-up right. A special make-up expert from France, Guillaume Castange, and his team were flown in to help achieve the right look.
Anupam, who started his film career in the 1980s and came into prominence with "Saaransh" where he played an aged, grieving father though he was just in his 20s, says it is important for him to push his limits as an actor, the reason why he wanted not just one but two roles in the film.
"It's an actor's triumph to do an antagonist and the protagonist in the same film. Initially, the makers came to me only with the role of the bad uncle.
After hearing the script, I told them that I will do the film only if I get to do both the roles. So they were horrified because it was a very unreasonable demand. But then they came back after two-three days and we discovered that we can work on it, " explained the multiple award winner.
"As an actor, I need to push my limits now. I have done so much work that unless and until I make it challenging, it does not excite me and obviously won't excite my audience.
"It is easier to think like that but very difficult to translate into reality because I'm an impatient person. So to sit down for five hours for the makeup and getting both characters right was difficult, " he added.
"Zokkomon" also stars Darsheel Safary and Manjari Phadnis and is a live action adventure of an ordinary boy who finds the strength to face extraordinary challenges.
The film has been helmed by a debutant director; Anupam has no problems with that.
"I'm now the specialised actor for debutant directors. Whether it's Dibakar or Neeraj, I have worked with many new directors. Satyajit knew what he wanted. He is very focussed and I appreciate his guts to allow me to do both the roles. That showed his confidence not only in the film, but even in me. I had his backing throughout."
"Also I don't think good work comes out of scepticism. Good work comes out of faith and trust and I had total trust and total faith in him, " he added.
The film is slated to hit the screens April 22.