You haven't seen foreplay until you've seen Angelina Jolie and Brad Pitt beat the beautiful out of each other in “Mr. & Mrs. Smith,” a sly, comically serrated romantic thriller that uses deadly games of deceit and intrigue as a handy metaphor for marital infidelity.

Though screenwriter Simon Kinberg (“XXX: State of the Union”) receives original story credit, the script appears to be equally flavored by two previous “Mr. & Mrs. Smith” offerings: A 1941 Alfred Hitchcock screwball comedy with Carole Lombard and Robert Montgomery, and a short-lived 1996 television series starring Scott Bakula and Maria Bello as spies who pose as a married couple.

In the current incarnation, directed by “The Bourne Identity” action-maestro Doug Liman, the Smiths are deep-cover assassins who are really married but mutually ignorant of their shared line of work.

Naturally, this living of secret lives has taken a toll on their six-year marriage, which has grown cold and loveless as the spouses traipse off to various corners of the world to double-tap moles and blow up motorcades. In essence, they're cheating on each other, a possibility the filmmakers invite us to take literally in the film's early scenes.

After a late night at “work,” mild-mannered engineer John Smith (Pitt) returns to his leafy suburban New York home with a swipe of red on his collar (in retrospect, it ain't lipstick), while Jane Smith (Jolie) dons leather lingerie and makes furtive late-night visits to swanky hotels. Could her “temp agency” actually be some kind of high-class call girl ring?

Her clients should be so lucky. In fact, Jane's temp agency is a front for a cloak-and-dagger boutique commanded by a barely seen bureaucrat (Keith David from “Crash”) and staffed exclusively by gorgeous women (think “Charlie's Angels” with machine guns). Similarly, John's construction firm fronts a “Three Days of the Condor”-style franchise operation he shares with Eddie (“Old School” cut-up Vince Vaughn), a fidgety, love-scarred divorcee who might be the world's only professional killer who still lives with his mother.

The Smiths’ marriage continues to languish in a persistent vegetative state until John and Jane are unwittingly dispatched to terminate the same federal witness in a legal case that could be potentially embarrassing to their respective agencies. The target escapes, their covers are blown, and John and Jane realize that their marriage has been nothing more than a six-year sham.

Given 48 hours by their nemesis employers to “clean things up” — an ultimatum that manifests itself in a delirious sequence of shootouts, bombings and punishing, expertly shot hand-to-hand combat scenes — the Smiths naturally assume that they've reached the end of their relationship, but in endeavoring to kill each other, John and Jane stir up old feelings. In exchanging armor-piercing rounds, they enjoy a new sense of marital transparency. It's not the end of their marriage. It's the beginning.

Hitchcock's original “Mr. & Mrs. Smith” featured a similar conceit, but whereas while that film was about the romance-reviving joys of breaking rules (Montgomery only becomes attracted to Lombard after he realizes that their marriage was never on the books), this one turns on the delight of disclosure. A typical scene has Pitt and Jolie bantering about the real identity of her parents while leading three armored BMWs on a high-speed, metal-crunching car chase over the Long Island Expressway. It's a sexy, viscera-tweaking juggling act, and Liman — whose diverse resume includes “Swingers” and “Go” — pulls it off without a hitch.

Whenever a pair of co-stars engages in a real, highly publicized affair — as Jolie and Pitt allegedly have — they always run the risk of overshadowing their on-screen chemistry. That never happens here. For one, both of them are chemistry kits unto themselves. Secondly, they seem to have a genuine mutual appetite, whetted by Kinberg's spritzy, sardonic wordplay.

The film's moral that marriage is a drag-out battle — not between the spouses, ideally, but the world at large — comes to a rather flip, theatrical conclusion, but that's hardly grounds for annulment. If one is to enjoy “Mr. & Mrs. Smith,” one must anticipate and savor the moment when the Smiths drop their “War of the Roses” act and direct their arse-kicking talents outward. In that sense, Pitt and Jolie give us what might be the greatest scene of make-up sex in the history of cinema — not for what we see (very little, actually), but for the epic spat that precedes it.