(CNN) -- Tom Cruise has been a movie star for longer than he hasn't, and his latest mission improbable supplies ample evidence of the charisma and cool that have generated so many billions of dollars at the box office. Unfortunately, "Knight and Day" (terrible title!) also suggests why "Cruise being Cruise" has turned into too much of a good thing for many moviegoers.
Perhaps it's because Cruise only makes a film every couple of years now that he feels compelled to push this screwball spy caper beyond breaking point. But more likely, it's the itch to amp everything up to 11 and prove he's still got more than it takes to get the job done.
A pity, because Cruise has always been best when he's, well, Cruising. He's an effortlessly agile and dexterous performer, qualities easily overlooked in an actor, but which can be the making of a film star. An early Cruise picture went by the name of "All the Right Moves," and he might as well have taken it as his personal credo.
He seems to be in great shape; hard to believe he's not far shy of 50. When June (Cameron Diaz) bumps into Roy Miller (Cruise) at the airport, twice within 10 minutes, she's obviously pleased to find herself seated on the same plane. That's before the entire passenger list -- all four of them -- the cabin crew and both pilots try to assassinate her new acquaintance, without success, leaving the rogue agent to improvise an unscheduled landing in a cornfield.
It's a crazy setup, but director James Mangold ("3:10 to Yuma") relishes the lunacy and the excess, and especially how it contrasts with Cruise's soft-spoken good manners and his gallantry around June: He wants her to be comfortable, in so much as that's possible as they crash-land a plane full of dead people.
She wakes up from this nightmare as if from a dream, though the story only gets more fantastic as she's interrogated by the feds, "rescued" in a ridiculously reckless high-speed pursuit by Roy and shortly whisked off to Spain, Austria and a Pacific atoll that's off the grid -- until June foolishly answers her cell, instantly bringing down a fighter plane attack.
Much of this mayhem qualifies as good old-fashioned fun. It's not a stretch to believe that Mangold watched a Hitchcock picture once. He gets it that a dose of danger can be a turn-on (he even sees to it that June drinks a truth serum so Roy gets it, too). More than that, he appreciates the romance in the situation. What girl wouldn't want to be whisked off her feet and placed in harm's way by such a chivalrous guy?
But after that promising first act, "Knight and Day" sacrifices most of its suspense and its charm on the altar of action overkill. The default fallback on CGI (those fighter planes would look more at home in a video game) is symptomatic of the movies' enthrallment to over-stimulation (and over-simulation) at all costs. The film spends so long running around in ever-increasing circles, it seems to forget where it wanted to go with these characters, and the third act forfeits on its promise of reversals, settling instead for repetition and redundancy.
Let's keep things in perspective: At least "Knight and Day" raises the bar on "Killers," and it's more convincingly A-list than "The A-Team." This summer season, you could do a lot worse. But there's a creeping anxiety about this project, a tendency to over-compensate that speaks to underlying inadequacies.