June Havens (Cameron Diaz) finds herself swept up in a global adventure with mysterious Roy Miller (Tom Cruise)in the action comedy Knight and Day. (Frank Masi/Twentieth Century Fox)

Knight and Day is a dud dressed up in blockbuster clothing, striving for the combination of sexy action and humour served up in Mr. and Mrs. Smith but winding up closer in spirit to the recent bomb Killers.

Knight and Day’s ill-conceived romantic subplot never quite meshes with all the violence going on around it.

The movie starts out strong, with a set-up that seems loaded with potential for dark comedy. After a few awkward run-ins at the Wichita airport, giggly June Havens (Cameron Diaz) and debonair Roy Miller (Tom Cruise) find they are seated on the same flight. While June retreats to the loo to freshen up her flirting face, Roy is ambushed by bad guys, whom he swiftly takes down with impressive action-star skills. Greeting June afterward with a smile and a cocktail, Roy calmly informs her the plane is going down, and for a minute, Knight and Day looks like it will allow Cruise to send up his own steely Mission: Impossible persona, along with every other Bond-style hero who remains cool as a cucumber in the face of death.

Alas, that script is for someone else to write. Once Roy and June’s plane makes a crash landing in a cornfield, Knight and Day switches to autopilot, and screenwriter Patrick O’Neill gives the actors very little to do. Informing the hysterical June that she’ll soon be approached by dangerous people who work for the FBI, Roy draws her into secret-agent intrigue she wants no part of. She spends the remainder of the movie learning to fire guns and survive car chases, all the time wondering if Roy is a psychopath or the man of her dreams.

Roy and June race through the streets of Seville, Spain. (Frank Masi/Twentieth Century Fox)

The cockamamie plot centres on a powerful energy source known as the zephyr. Everyone in Knight and Day seems to want to get their hands on this battery-sized device, though it’s basically just an excuse to stage a series of action set pieces in exotic locales ranging from a tropical island to the Alps to Seville, Spain. In theory, this is everything you’d want from an espionage flick, but director James Mangold (Walk the Line) botches the pacing, piling car pursuits, fistfights and explosions one on top of the other to repetitive, mind-numbing effect. The movie’s CGI touches are also less than stellar – in one particularly silly scene, June and Roy look as if they’ve been grafted onto pre-existing footage of a Spanish street full of running bulls.

Cruise and Diaz are athletic actors, and they throw themselves into the numerous gunfights and hand-to-hand combat with enough gusto that you almost buy it. But they have a tougher go of it in the movie’s ill-conceived romantic subplot, which never quite meshes with all the violence. Not only that, it often borders on creepy. Stepping in at key moments to protect June from danger, Roy repeatedly drugs his damsel, changes her clothes and drags her off to new locations. This bizarre form of courtship only makes June more smitten. While this conceit is played for laughs, it doesn’t make much sense, and I spent the entire midsection of the movie trying to figure out whether June was a masochist or just the world’s dimmest female.

Knight and Day is too busy to waste time on character development, a lesson that gifted supporting players like Viola Davis, Paul Dano and Peter Sarsgaard learn the hard way. The movie clearly aspires to be nothing more than big, dumb summer popcorn fare, a goal it almost achieves due to the sheer charisma of its leads. The script has obviously been tailored to suit their individual strengths (and limited ranges), with Diaz delivering her trademark ditzy comedy and Cruise doing his cocky, shades-wearing hero bit to perfection. Dodging explosions in swimwear, they’re a life-sized Barbie and Ken — as slick, eye-popping and hollow as everything else going on in Knight and Day.

Knight and Day opens June 23.

Lee Ferguson writes about the arts for CBC News.