Had Michael Douglas and Kathleen Turner worked as secret assassins in 1989's "The War of the Roses," the outcome probably would have ended up a whole lot like "Mr. & Mrs. Smith." Following his work on 2002's "The Bourne Identity", director Doug Liman shifts tones, if not exactly gears, to unite two of Hollywood's biggest A-list actors for an alternately pompous and acerbically funny look at a highly dysfunctional marriage. "Mr. & Mrs. Smith" works in fits and starts—for every on-target scene of cleverly truthful humor, offbeat romance and well-modulated action, there are almost as many that either hit a false note, go on too long or expose some uneven plotting. As pure glossy entertainment, though, it more than does the trick.

John (Brad Pitt) and Jane Smith (Angelina Jolie) are a straightarrow couple living in the Long Island suburbs whose marriage over the past five or six years—the length of their relationship is a constant source of debate—has significantly deteriorated. Sexless, typical and bored, they go through the motions of their comfortable lifestyle, but there is no joy between them anymore. Their rocky romance is put to the ultimate test when both parties discover each other have long since been secretly working as assassins, lying about who they really are from day one. Worse yet, when John and Jane accidentally come face-to-face during an attempted hit, their agencies put the pressure on them to knock the other out of the equation or risk their own lives. As a fight to the death begins, the impending finality of their relationship gradually forces both of them to reconsider just how much of their marriage was a put-on and how much was true love.

It isn't often that two movie stars of the caliber of Brad Pitt (2004's "Troy") and Angelina Jolie (2004's "Alexander") join forces for such a big, tailor-made Hollywood crowd-pleaser, or maybe it just seems that way because few on-screen couples share the amount of innate chemistry and sense of fun that these two do. Looking at Pitt and Jolie together is enough to make anyone envious—they are both inconceivably beautiful people—but they also turn in surprisingly loose, comedically potent performances that carry "Mr. & Mrs. Smith" through its weaker moments. Jolie is especially funny right from her very first appearance and without having to say a word, which is something most viewers may not be expecting from a performer that usually seeks out more serious roles. And, to top things off, Pitt and Jolie simmer and sizzle together, working as a real team and relating to one another on an emotionally involving level.

The screenplay by Simon Kinberg (2005's "xXx: State of the Union") gets just right the tiny details of a long-term relationship, and the roadblocks of connection and intimacy that are bound to arise. This awkward, but realistic, detachment only makes their ultimate rekindling all the more satisfying and sexy. At the same time, Kinberg could have used another rewrite or two, because in between the slice-of-life relationship moments is a plot that feels overblown and shaky, turning down some very dark paths as John and Jane try to kill each other, intermittently making them unbelievably cold. Whether or not they have been lying to each other about their professions and background does not mean that their marriage has been a sham, which makes their abrupt turning on each other feel unbelievable.

After a plot development at the beginning of the third act turns the screws of the story once again, director Doug Liman regains footing and a semblance of a beating heart for his characters just in time for a finale filled to the gills with large-scale car chases, shootouts and myriad pyrotechnics that boast real showmanship. In keeping with its off-and-on quandary, the very ending appears unfinished and sloppy, cutting to credits before screenwriter Kinberg has a chance to wrap up a number of key story points. By these last scenes, nothing has really been satisfactorily solved, even as the core of the film—John and Jane's marital relationship—does hit the right notes without going saccharine.

"Mr. & Mrs. Smith," which has adult summer blockbuster written all over it, is so bewitching as a romantic, charged and aesthetically slick star vehicle that it is easy to turn a blind eye to its shakier aspects. The cross-assassination plot is more hindrance than help, and more minimally, the inappropriate filming locations used make the physics of travel confusing. For example, John and Jane's house, previously used in "A Nightmare on Elm Street," is located in real life in one of the most famous West Hollywood residential areas, which doesn't gel with the otherwise Manhattan-area settings. By the time I realized the neighborhood was meant to be in Long Island rather than L.A., and John and Jane weren't commuting to the east coast as initially suspected, the movie was half over. While not a major problem, a simple line of dialogue—or a different choice in location—could have cleared this misunderstanding up. Flaws and nitpicks aside, "Mr. & Mrs. Smith," filled with cute little in-jokes (a character played by Adam Brody shares a scene with Brad Pitt while wearing a "Fight Club" shirt) and a whole lot of energy, is a trip worth taking, if only to gaze at Brad Pitt and Angelina Jolie for two hours and wonder just how two human beings can stay so pretty even with bloody cuts and bruises all over their faces.