Bryan Cranston relished role as blacklisted Communist screenwriter Dalton Trumbo

TORONTO – Bryan Cranston loved playing Dalton Trumbo so much he didn’t want to stop.

Even in the midst of the tiring press cycle at September’s Toronto International Film Festival, the Golden Globe winner needed only the slightest provocation to hunch his body, flatten his voice into a nasally sprawl, and dive into a first-rate impression of the famed Hollywood screenwriter.

But given the film’s occasionally solemn subject matter — Trumbo was jailed and blacklisted for his supposed Communist ties — Cranston was careful not to let his depiction lapse into all-out caricature.

“I tell my director Jay (Roach), I said: ‘I need to go out on the limb…. I’ll keep going out on that limb until we hear it breaking, and then pull me back,'” Cranston said during the festival. “You have to go there to say: OK, that’s too much. Bring it back and try to find the sweet spot.

“So yes, he was a very flamboyant man, with affectations and the cigarette holder and the way he gesticulated,” added Cranston, cheerfully transforming into Trumbo in both voice and posture, “and he would pontificate about many, many things and he loved to hear himself talk.

“So he was not a man without tremendous ego, which makes (him) an interesting character to play. I loved playing him.”

Trumbo was the furiously prolific screen scribe who became the highest-paid writer in Hollywood on the strength of ’40s hits “Thirty Seconds Over Tokyo,” “Our Vines Have Tender Grapes” and “Kitty Foyle,” which merited his first Oscar nomination.

He officially aligned himself with the Communist Party in 1943, and as that political alliance fell out of fashion, he became a target of the House Un-American Activities Committee.

With his round-frame glasses, slender moustache, dangling cigarettes and dancing voice, he became perhaps the most distinct and outspoken member of the so-called Hollywood 10, who were blacklisted from Hollywood for their supposedly dangerous views.

After a year-long prison stint — served because he refused to testify to Congress — Trumbo began issuing scripts under a series of pseudonyms. He even won an Oscar for one of his anonymous creations, “The Brave One.” (He would later write “Spartacus,” “Papillon” and “Exodus.”)

Though the story of a wildly creative man that is jailed, humiliated and driven to near-poverty over his political beliefs might sound harrowingly dour, “Trumbo” is sprightly paced. It features a cast that includes Louis C.K., Helen Mirren and John Goodman, who plays the strident Frank King, who employs Trumbo when others won’t.

“It’s not a topic people think necessarily they’re going to come running to, over the latest Marvel movie or something,” conceded director Jay Roach.

“But if they do, I don’t think they’ll be disappointed.”

Even with the impressive cast, it’s Cranston’s film.

Over the course of the movie, Trumbo begins to wither under the pressure of supporting his family without the benefit of his name to sell scripts. He chain-smokes in the bathtub, pops methamphetamine tablets and churns out script after script, barking angrily at whichever family member has the gall to interrupt his routine.

“I pride myself on willingness to engage in conflict, in battling for getting your point across, or fighting for an element of a story that’s important to me, said the 59-year-old actor.

“I’m very passionate. I love to work. I love storytelling.”