By the time he made “The Purple Plain,” Gregory Peck had already made a film that touched on the fear and emotional toll of air combat in World War II — 1949’s “Twelve O’Clock High.” But the text of that Henry King classic buried subtexts like those under patriotism, mission and “morale.”

“The Purple Plain,” coming out five years later and featuring the star of Hitchcock’s Freudian “Spellbound,” is a little more psychologically “evolved. The mental cost of combat wasn’t a subject the movies easily embraced, but by the ’60s, when Steve McQueen starred in “The War Lover” and “Lawrence of Arabia” swept the Oscars. Filmmakers and viewers had enough distance from the WWII to consider wrestle with more sophisticated dramas than the avalanche of action films set in combat zones.

Child actor turned Oscar-winning-editor (“Body and Soul”) turned-journeyman director Robert Parrish took cast and crew to Ceylon (Sri Lanka) for one of his best films, a study in post traumatic stress and an old fashioned “behind enemy lines” survival trek through Burma.

Peck stars as Bill Forrester, a Canadian-born Battle of Britain veteran now flying a Mosquito fighter-bomber heedless of the extra risks he’s taking. When we meet him, he gets his navigator wounded by recklessly breaking formation to strafe and pound Japanese anti-aircraft batteries.

It’s 1945, and while the slow slog through Burma might not give those doing the fighting this sense, much of the world could see World War II was nearly over. Forrester doesn’t care. He’s driven to fly by day, given to night terrors, awakening to imaginary air raids when he sleeps.

“Gone round the bend,” the Brits around him say. A flashback tells us he never got over losing his wife in a London air raid during The Blitz.

“I didn’t want to go on living. You’d think that would be easy enough in war but it didn’t work. I wanted to die but I got medals instead.”

Future James Bond boss Bernard Lee plays the unit doctor charged with doing a “medical evaluation” that doesn’t look like one. His non-flying tent-mate (Maurice Denham) thinks the lack of something or someone to look forward to is driving Forrester’s behavior. The doc figures dragging Forrester to the Christian mission for Burmese refugees will teach him a thing or two.

Victims of the war, uprooted by the Japanese, the natives are resilient. They have trauma, too, as evidenced by their panic that an air raid means the Japanese are advancing back over this reconquered ground. But a pretty young woman (Win Min Than) simplifies the human need to persevere after tragedy for Forrester.

“Here we bury the dead in the earth not in our hearts.” 

Forrester allows himself to feel something, even if he can’t shake the bullying cynicism that has him lashing out at subordinates who get to “ship out” when he’s manic to keep taking deadly risks, flying and fighting.

It’s a “milk run” mission, flying to break-in his new navigator (Lyndon Brook) while delivering tentmate Blore to a new assignment that leads to a crash and their fight to survive in an arid corner of the country, far from water, food and friendly forces.

Forrester keeps making impulsive command decisions about two of the survivors dragging their wounded comrade for days and days to safety. Their quest will give him cause to reflect on that decision, what motivates him now, and whether or not he’s made the sane, rational, survivable choice.

Peck’s performances often have a stoic reserve to them that was not to every taste. But he rarely played “dumb” for a reason. We see wheels turning in most every performance, even when he’s playing characters out of their depth or outside of his persona’s comfort zone.

He’s giving us a lower-rank variation of the same testy bomber group leader he played in “Twelve O’Clock High,” a character of vulnerabilities and easy-to-read psychosis.

Peck made this movie to dodge U.S. taxes. But his vulnerably heroic turn here is empathetic and layered, making it worthwhile as he plunged into his peak decade a screen star.

There’s a hint of the patronizing side of racism in the “Onward Christian Soldiers” singing refugees mission director (Brenda de Banzie), tempered by Scottish good intentions and charity. The enemy here is unseen, and Forrester’s “courtship” of a native woman is understated to an almost timidly genteel degree.

Parrish’s direction is spare and unfussy, making the most of the exotic location and the combat setting (real Mosquitoes do most of the flying). Geoffrey Unsworth’s cinematography is pretty enough, but only giving the barest hint of the Oscar-winning giant of his field he would be become. “Becket” to “2001” to “Cabaret” to “Superman” to a final Oscar for Polanski’s lavish ’81 period piece “Tess,” he was one of the best ever.

“The Purple Plain” was a decent hit in the U.K., and somewhat forgotten stateside. But producer J. Arthur Rank went to school on this Ceylonese shoot. He was encouraged enough by the striking location and Ceylon’s film-friendliness that he’d send David Lean there to film a WWII masterpiece, “The Bridge on the River Kwai.”

As with his ambitious all-star Caribbean drama, “Fire Down Below,” Parrish found himself filming a test run in a challenging place for a producer (James Bond-backer “Cubby” Broccoli on “Fire”) who would make his real mark with better pictures in that same now-proven location in the future.

At least “The Purple Plain” holds up well, a solid genre picture with a more enlightened take on the cost of combat for those who fought it than most WWII films could manage back then.

Rating: approved, TV-PG, combat violence

Cast: Gregory Peck, Win Min Than, Brenda de Banzie, Maurice Denham, Lyndon Brook and Bernard Lee.

Credits: Directed by Robert Parrish, scripted by Eric Ambler, based on an H.E. Bates novel. A J. Arthur Rank Org. release on Tubi, other streamers

Running time: 1:40