Nawazuddin Siddiqui is like a mix of shades, of mostly subdued hues. This isn't about what he is wearing, but pretty much all else. I am at the plush five-star lounge, rehearsing in my mind the questions I would ask him, one of my few favourite actors. Suited executives move about swiftly, ensuring everything is in order - the cups, the shining pots of tea and coffee, the fine cookies, the sofas. After all, Nawazuddin is hot property these days, in a league quite his own. He is in the city to attend the Tata Steel Kolkata Literary Meet, where he has a session with Nandita Das on their forthcoming Manto.

But then someone informs that the actor will not meet us in the lounge but outside, by the pool. Style, I think. But when I see him there, I realise I got him quite wrong. He chose this spot because it is comfortably shadowy and the ambience discreet. Some of the cane settees are occupied, but I bet none knows Nawaz is amongst them.

I am introduced to him by the lovely woman taking care of appointments. "They do very serious features," she quips. " Haaaaann?" he sits up, startled. I ignore my friend's wicked laughter, but his reaction tells me a precious bit - within the towering actor is a most unassuming man.

We begin by chatting about Calcutta, the city that has framed some of his very important films - Kahaani, Anwar Ka Ajab Kissa, Te3n... He recalls the Metropole Hotel on Sarat Bose Road, where they shot much of Kahaani. "They would tell me to stay at the Taj, but I preferred this little hotel with a cafeteria on top. That one that's very close to Basonti College [Basanti Devi College]... You know?" he asks eagerly. I couldn't help but nod a smile.

But what about Anwar Ka Ajab Kissa? Directed by Buddhadev Dasgupta, this dark comedy still awaits release, although it was much applauded at the 2013 BFI London Film Festival. "I played a small-time private detective who is in search of himself. I have no idea why it wasn't released. But working with someone like Buddhadev Dasgupta was wonderful..."

Later, I learn from Dasgupta that the censor board is not to blame this time - it has cleared the film - but the director, too, cannot say why it is stuck. What he does say, however, is that Nawazuddin is at his best in it. "He was relatively fresh then. He stayed in my house for a week - he doesn't like big hotels. I would let him talk, uninterrupted, and slowly realised that he is a lot like Anwar," Dasgupta says of him fondly. "Given the right kind of work, I think Nawaz is next to none."

Nawazuddin does bring out the dark best. I tell him as much, but he doesn't agree. "These are not dark characters," he corrects me. "They are all shades of grey. And that's the closest we can get to the human condition." I can sense this is a subject on which he can go on, such is the conviction. "I see no role as negative or positive, in the same way that you may have both plusses and minuses," he says looking at me.

But isn't Raman Raghav totally dark? "Yes. And playing him was one of the toughest times of my life." The thriller is based on the story of a psychopathic serial killer in Bombay of the mid-60s. "Reel life and real life had become one - I couldn't differentiate one from the other... The strain was unbearable, I fell ill and needed to be hospitalised. So I was given an eight-day break."

It was widely reported at that time how playing a psychotic killer had crushed him. And how, when his wife visited him in hospital, he was unconscious yet murmuring dialogues from a particular scene. "I had travelled so deep into the character that it was difficult for me to come out it," he says, and mutters, as if not wanting me to hear, " Bahut nuksan kiya Raman Raghav ne mera."

However, donning one character after another is usually not a problem for him. "I give myself a month's gap before embarking on a new role... This segregation is important to me. There are then no remains of the previous character, and I can start from zero."

The actor's diary is choc-a-bloc. He has an upcoming Web series by Netflix - called Sacred Games, also starring Saif Ali Khan and Radhi-ka Apte. In this, he plays a Marathi gangster called Ganesh Gaitonde. Then there is the British Web series, McMafia. "It's being made on a grand scale," says he. "There are actors from all over the world - Russian, Israeli, European, British, Hollywood... I am also there, it's an important role." There is definite buoyancy in his demeanour.

With so much cinema being thrust on you - Netflix, Web series, TV channels, multiplexes - it does get a bit overwhelming for old timers. The film-watching experience isn't what it used to be, I lament, hoping that he would see my point. But he disagrees again. "Look, the choice is yours - what you want to see and what not. As for me, I do only one film at a time." Well, it only means that this man is here to take ownership of every inch of screen time.

Nawazuddin is not a "talking" actor. It's as though he possesses a fine art, but which he cannot express in words. Somewhere in the middle of our conversation, he says, "Acting is basically a simple thing." But to know what "simple" means here, one must see it through his eyes.

One of his best screen moments, the fan girl in me tells him, is in Badlapur. Here he plays Layak, a convoluted criminal mastermind who very slowly yields to a more humane and vulnerable character. In the climactic scene in a prison cell, when he and Raghu (Varun Dhawan) are face-to-face, one is completely awestruck by the powerful drama on Layak's ageing face - the cynical fulfilment of being able to script the last word, despite it all. While we are talking about this, I see a shine in his eyes.

M anto is in post-production; and will release May-June, he hopes. Then there is the one film everyone has their eyes on - Thackeray. Reams have been written about the irony of the casting. After all, it wasn't long ago that Nawazuddin had to pull out of the Ramlila performance in his hometown, Budhana near Muzaffarnagar, Uttar Pradesh, following objections by the local Shiv Sena.

"Manto and Balasaheb are extreme opposites... Didn't you feel iffy about accepting the role of Bal Thackeray?" I ask a bit sheepishly. "Why?" So I put it this way - "Aren't you uncomfortable with the Shiv Sena's extremism?"

"But I am playing a character, and a fascinating one at that. World ka koi bhi actor, jise yeh role milega, chhodega nahin. (Any actor from any part of the world would grab it.) I see a huge opportunity for myself in it."

I decide to prod further. Many actors have over the last couple of years raised their voice against the rising incidence of intolerance in the country. Did he ever feel the need to do the same?

"God scripts each person a role before he sends him to earth. Mine is to act. Upparwala ne mujhey yehi kaam diya hai (God has given me this role to play)," his words are well rehearsed. "And if ever I feel the need to say something, I will make a film on it... that is the only medium I know."

So the man is reading up all he can on the life of the Shiv Sena supremo. And it's not going to be an easy job, he admits. "But I have some time on my hands and I am willing to slog it out." Shooting begins end of March. The next film we will see him in is Photograph, directed by Ritesh Batra, who had directed him in The Lunchbox. " Dangal girl Sanya Malhotra is my heroine," he says. "Uska aur mera romance hai."

In India, most film lovers have grown up on a diet of Bollywood. What kinds of films did he see in his younger days? "In those days, there were no theatres in Budhana. We had to walk a long distance to be able to see movies. And those theatres only screened C-grade films... We grew up watching C-grade movies."

Is there any particular role that he'd want to play? I had read somewhere that he was in awe of Ashish Vidyarthi's character in Drohkaal, a 1994 crime thriller directed by Govind Nihalani. "That was then," he says gently. "As the years roll by and new examples are set, my favourites too change." And what would that be? "I wish I could do something like what Leonardo DiCaprio did in The Wolf of Wall Street."

With people like Nawazuddin, you have to keep on prodding, braving it all the way. And then there are even moments when he looks bored! But time is running out; there are others waiting. As I leave, I see two schoolchildren ready to jump in, pen and notebook in hand. And I hope they bombard him with questions and take the breath out of him.