2 GUNS (Rated R)

An action picture, packed with suspense and violent thrills, should contain surprises that are not revealed in the promotional trailers. That’s not the case for the buddy caper “2 Guns.”

Fortunately, Denzel Washington and Mark Wahlberg have such good chemistry that the central conceit that their initial foray into a seemingly criminal act of robbing a small town bank is a cover for their undercover mission does not spoil what follows.

When the film opens in a dusty Southwest town, Washington’s Bobby Trench and Wahlberg’s Marcus “Stig” Stigman are bickering about what to order for breakfast while getting a sense of the lay of the land and plotting their moves.

Smooth as silk, Bobby is calm and the clear-headed thinker. In contrast, Stig, a fast-talker, is given to making wise cracks at inopportune moments, and he loves to flirt and wink at pretty waitresses, even though he comes up short in the romance department, at least compared to his comrade.

The object of the Tres Cruces bank robbery is to steal $3 million in the bank vault belonging to Papi Greco (Edward James Olmos), the sleazy head of a Mexican drug cartel who appears to operate with impunity.

While planning the robbery, neither Bobby nor Stig knows that his partner in crime is an undercover agent. Bobby is a DEA agent and Stig is a naval intelligence officer. Both were charged by their superiors to infiltrate the drug cartel.

Additionally, of course, neither agent knows that they’ve been set up, as they believe the goal of the caper is to put a dent in Papi’s operation, causing him to emerge from the shadows and expose his vulnerabilities.

Surprisingly, the safety deposit boxes contain more than $40 million in cash, and after Bobby and Stig make off with the loot, assorted bad guys and dubious government operatives give chase.

As befitting a caper film, the folks who materialize out of the woodwork are often mysterious. For instance, Paula Patton’s Deb, a DEA agent who has been at times romantically entangled with Bobby, is a player in the complex web of secrecy and possible deceit.

Yet, aside from Papi Greco and his trigger-happy henchmen, the most serious threat to Bobby and Stig is the sadistic Earl (Bill Paxton), a CIA operative, who may well be a rogue agent but is viciously committed to retrieving the purloined booty that supposedly belongs to the CIA.

Meanwhile, Stig is also being pursued relentlessly by corrupt Navy officer Quince (James Marsden) whose motives are unknown, except possibly he just wants the whole share of ill-gotten fortune for himself.

The villains in “2 Guns” are a menacing bunch, often to cartoonish effect. At Papi’s Mexican ranch, the head of a rival is found stuffed in a bag. Equally brutal, Earl loves to play Russian roulette while interrogating people.

The plot is complicated by a slew of double and triple crosses, but mostly it is all about the chases and shoot-outs, along with the occasional explosions, whether blowing up a diner or a classic car stuffed with illegal cash.

Since the true identities of Bobby and Stig were revealed so regrettably by the film’s advertising, the least we can do here is not give away too much about the unfolding of the convoluted plot.

What is apparent, however, is that Bobby and Stig are entangled in a growing number of intricate plot twists that put their very lives at risk, and so most of the action becomes an elaborate survival effort on their part.

The best thing about “2 Guns,” aside from the fact that the action is clever and entertaining, is the evolving buddy relationship between the two lead characters.

Denzel Washington and Mark Wahlberg make an amusing odd couple, the best of their scenes being when they quarrel about plotting escape moves and banter about the seemingly innocuous and mundane aspects of daily life.

Director Baltasar Kormakur, a native of Iceland, has produced and directed many films known mostly in his homeland, though he directed “Contraband,” which also starred Mark Wahlberg.

Though I have no factual basis for making this claim, the Icelandic director seems to have been inspired by American action films like the original “Lethal Weapon” and “The Last Boy Scout.”

Regardless of cinematic influences derived from the past, Kormakur’s “2 Guns,” though it may be outlandish, is a very enjoyable buddy caper, with great action and plenty of humor.

Tim Riley writes film and television reviews for Lake County News.