Throughout David Ignatius' 2007 novel Body of Lies, you can feel the potential for creating something ... deeper. While the surface markings were those of an age-of-terrorism espionage thriller, there were also hints of Mystic River author Dennis Lehane -- the portrayal of a world in which moral decision-making was virtually impossible, and the best a soul could hope for was to make the least immoral decision. But whenever these ideas seemed ready to bubble over into something seriously probing, Ignatius would fall back on over-plotted genre convention.

Director Ridley Scott's adaptation -- working from a script by William Monahan (The Departed) -- at times teases with the same promise of piercing insight into a no-win situation. And while the film strips away much of the fat from Ignatius' storytelling, it also winds up frustratingly superficial. It's a nuts-and-bolts action drama putting on the undercover persona of something with a message.

Not that it isn't fairly successful as an action drama. Scott plunges into the story of Roger Ferris (Leonardo DiCaprio), a CIA field agent working on the ground to recruit "assets" -- secret operatives -- within terrorist groups in Iraq. But he always seems to be working at cross purposes with his boss Ed Hoffman (Russell Crowe), an impatient hawk who barrels in with guns and attitude blazing where others fear to tread. This clash becomes a particular problem once Ferris begins an assignment in Jordan to find Al-Saleem (Alon Abouthoul), the secretive terrorist leader responsible for a series of bombings in Europe. And this mission will require Ferris to work with Hani (Mark Strong), the Jordanian intelligence director with no fondness for typical American pushiness.

Monahan's structural tweaks mostly serve to streamline the narrative, including removing most of the material involving Ferris' strained marriage and, curiously, the undercover operation that gave the novel its title. But he also beefs up the role of Hoffman for Crowe -- who, in turn, beefed up to play the jowly bureau chief. And Crowe does a fine job as a guy who makes life-or-death decisions a world away via his cell phone while standing on the sidelines at his daughter's soccer game. Body of Lies effectively juxtaposes Hoffman's bird's-eye-view sense of omniscience -- he watches all from spy plane surveillance, while at times knowing nothing -- with the hazardous shoe-leather intelligence-gathering of Ferris, whose efforts put him in the way of human shrapnel, angry dogs and the business end of a ball-peen hammer.

But more Hoffman inevitably means less Ferris, and there's something missing from both DiCaprio's performance and the character. While Ferris is supposed to serve as the voice of reason -- the guy whose knowledge of the region might get results if his higher-ups would ever butt out -- Body of Lies doesn't ever really get inside his head. Ferris' relationship with an Iranian-born nurse (Golshifteh Farahani) is meant to soften his own brand of icy pragmatism, but there's not enough time to develop it into something that explains the self-sacrifice he's later willing to make on her behalf. After 128 minutes spent with Roger Ferris, I can't really say that I understand what makes him tick.

It's fortunate, then, that Body of Lies can at least tick along as a tense little thriller. Scott knows how to wrangle nervous energy out of both bullet-riddled chases and silent waiting, and he's never been shy about using a little excruciating damage to a human body to make a point. Monahan's script maintains a clean, crisp trajectory through the narrative, and finds enough space for even the clash of wills between Ferris and Hoffman to drive the action.

What Body of Lies is missing, however, is a broader sense of consequence. It conveys, in its way, the consequences of an American intelligence apparatus that relies too much on technology and too little on the wisdom of its knowledgeable people on the ground, but even that point gets muddled when Ferris uses high-tech identity theft as a way into Al-Saleem's operation. It's a story that often seems poised to tell us more about why the War on Terror has turned into such a quagmire, then retreats to the relative safety of explosions and shouting matches. Like Ignatius' novel, the film version of Body of Lies winds up sidestepping the thorniest questions -- observing, like Hoffman, from too safe a remove.

BODY OF LIES

**1/2 (two and a half out of four stars)

Starring: Leonardo DiCaprio, Russell Crowe, Mark Strong.

Directed by Ridley Scott

Rated R.