Starring in the one-shot war epic “1917,” which releases on Dec. 25, Benedict Cumberbatch has maintained a busy schedule. Appearing in a multitude of upcoming movies, from “The Tiger Who Came to Tea” and “Louis Wain” to “Prisoner 760” and “Doctor Strange in the Multiverse of Madness,” Cumberbatch has a great many shoes to fill.

For his next film, for which he is also on as executive producer, fans will see the 43-year-old actor become a spy named Greville Wynne in Sundance’s new drama “Ironbark.” Cumberbatch sat down with Entertainment Weekly to discuss the forthcoming project and to explain what the world of the “Ironbark” movie looks and feels like.

“This is a story of a very average hero,” said Cumberbatch. “He was just a charming Welshman with the gift of the gab.”

For those wondering what is "Ironbark," Cumberbatch’s new movie will explore a dangerous Cold War espionage scheme that will see his Greville Wynne turn from an industrial goods salesman to MI6 messenger. Wynne must work alongside a Russian contact, named Oleg Penkovsky (Merab Ninidze), which leads to a remarkable friendship.

“[Greville Wynne] literally goes from being a rather charming businessman heading towards retirement, with a good sense of humor and a jolly manor, to being someone who is basically secreting Minox film cartridges about his case as he tos-and-fros to Moscow under the guise of being part of a British delegation of trade,” the actor said.

Among the most daunting of tasks for Cumberbatch was getting the “sort of strange Welsh accent” just right. Next to perfecting his accent, Cumberbatch had to endure some unrelenting shoots, like a winter expedition in Prague, which saw Cumberbatch “semi-naked in real ex-prisons” at below-freezing temperatures.

“It’s nothing compared to what [Wynne] went through,” Cumberbatch humbly added.

“Ironbark” marks the third time Cumberbatch has worked alongside director Dominic Cooke, including BBC Two’s “The Hollow Crown” and the Royal Court Theater’s “Rhinoceros.” Cumberbatch explained all it took for him to leap on board was for Cooke to detail Wynne’s emotional story.

“It is possible for us to be ordinary people that are capable of doing extraordinary things when the time comes, when the questions are asked,” Cumberbatch explained on the nature of “Ironbark” and its rudimentary theme. “I think that’s what it is – it’s quiet heroics in a very loud world.”

Dive into the Cold War on Jan. 24 as “Ironbark” premieres at the Sundance Film Festival.

Benedict Cumberbatch
Benedict Cumberbatch is pictured here at the Laureus World Sports Awards show on April 15, 2015 in Shanghai, China. Getty Images