4Among his many roles, Clive Owen has portrayed Sir Walter Ralieigh and King Arthur. But becoming Ernest Hemingway in the new HBO romantic film, “Hemingway & Gelhorn,” he says, “was a huge challenge.”

“I took a lot of time off before, to get ready for it,” Owen told reporters earlier this year. “I did a lot of research. I read everything. I immersed myself as much as I could.”

Hemingway, Owen says, was “very much a part you have to attack.” Still, he says, he had to be careful not to go over the top.

He plays opposite Nicole Kidman, who portrays the war correspondent Martha Gelhorn, who became Hemingway’s third wife.

“Martha found her voice when she was with Hemingway,” Kidman says. “He was a big part of helping her to, as he says in a line in the film, get in the ring and start throwing some punches for what you believe in.”

Kidman says she was inspired by Gellhorn, who was one of the first female war correspondents.

And
 as she did playing another writer, Virginia Woolf, Kidman says “I learned from playing her. It was kind of a necessity in that, in the journey of my career, to find these women at times, and tell their stories. And it’s a blessing because, you know, they’re very hard stories to get made a lot of times.”

The road for “Hemingway & Gelhorn,” directed by Philip Kaufman, was typically circuitous. It was originally meant for a big screen theatrical release but in the end is making its debut on HBO tonight.