Be careful what you read about “The Debt,” since even a cursory summation of its plot may reveal twists that the movie has been carefully constructed to conceal. It’s not an emergency on the level of, say, not finding out before seeing “The Empire Strikes Back” that Darth Vader and Luke Skywalker are (anger, fear, egregious spoilers of 30-year-old movies — the Dark Side are they).

On the other hand, it seems likely that a thoughtful viewer’s enjoyment of “The Debt” would be heightened by confronting its biggest dilemma in the same moment that that predicament is thrust upon its young protagonists. And what a welcome development it is to need to caution anyone about a tense, thrilling action movie that includes heavy-duty thinking among its pleasures.

Stephan Gold, David Peretz and Rachel Singer are highly trained operatives in Israel’s Mossad, also known as the Institute for Intelligence and Special Operations. The movie uses two sets of actors to follow them at separate periods in their lives, first in 1966 as they hunt for a Nazi war criminal in East Berlin, and then again in 1997, at a point when Stephan remains involved in the Mossad, but David and Rachel have moved on.

In 1966, the trio are very, very close to concluding a 15-year hunt for Dieter Vogel, the notorious “surgeon of Birkenau.” In 1997, they are famed for the outcome of that operation, but worn down by the intervening years and clearly still troubled by aspects of what happened in Berlin long ago.

The Berlin flashbacks are tight, suspenseful and relentlessly driven by steely, focused acting from Marton Csokas (as Stephan), Sam Worthington (David) and Jessica Chastain (Rachel). Worthington, brawny but bland in films like “Clash of the Titans” and “Terminator Salvation,” shows himself capable of handling much more than he’s typically been given, while Chastain, earthy in “The Help” and ethereal in “The Tree of Life,” continues a banner summer by seeming coolly detached at one moment, vulnerable the next, and never a speck less than competent.

Vogel, a screenwriting creation clearly modeled after actual Nazi “researcher” Josef Mengele (who died a free man in Brazil more than 30 years after World War II), is a properly harrowing scourge for the nightmare existence in a cramped, leaky flat that has Stephan, David and Rachel under constant strain.

Jesper Christensen plays Vogel in a performance of such nasty brilliance that he manages to seem equally sinister whether raving about his crimes, or caught up in the simple act of conducting a gynecological exam.

The action in the film’s present day is more subdued, and more internal, but no less spurred by the emotion that smolders in the eyes of its characters. Helen Mirren, as Rachel, has a larger part than either Tom Wilkinson (Stefan) or Ciaran Hinds (David), but all three actors are believable in the level of their acceptance or rejection of their shared past. Hinds’s astonishing first scene is played out almost entirely by means of his hooded, haunted gaze.

The film uses a narrative structure that shuffles time like a deck of cards, but director John Madden and his trio of writers (Matthew Vaughn and Jane Goldman, with rewrites by Peter Straughan) are in the camp of filmmakers who can make the endless card tricks seem elegant — there’s an especially masterful cut between passport photos of present Rachel and past Rachel — and, more to the point, the gimmick serves their story.

The movie’s technical credits are smooth and assured from start to finish. Thomas Newman’s urgent score is like a properly muffled outboard motor, propelling the film’s action without drowning it out. And the crisp cinematography by Ben Davis cannily divides the film’s appropriately murky past from its more brightly lit present.

“The Debt” asks big questions and lets us stew about the answers to them. The characters take various actions at various times — I’m being deliberately vague — and it’s up to the viewer to decide whether some are warranted, others misguided, still others confused by emotion and shifting loyalties.

It’s greatest mystery, actually, may be what on Earth it’s doing here now on one of the historically weakest moviegoing weekends of the year. Originally intended to be released last December in the full heat of the 2010 Oscars race, “The Debt” has become essentially a cinematic afterthought. Whoever made that call is wrong. Moviegoers shouldn’t need their own intelligence service to find the films that are this good.

Grade: A

Director: John Madden

Cast: Helen Mirren, Jessica Chastain, SamWorthington, Tom Wilkinson

Running time: 1 hr., 54 min.

Rating: R for some violence and language

Location: Opened Wednesday at theatersnationwide