It's amazing what you can do with charisma.  It can elevate a mediocre movie to greatness and elevate a bad movie to mediocrity.  Knight and Day is a case of the latter.  The film's overly-long, paper-thin plot and misogynistic undertones are combated by Tom Cruise's sheer force of personality, his chemistry with co-star Cameron Diaz, and James Mangold's skill for shooting exciting set pieces.  These elements combine to make Knight and Day a better movie than it should be, but unfortunately aren't enough to make it as good as it could be.

Everywoman June Havens (Diaz) is drawn into a web of international intrigue after a chance encounter with rogue spy Roy Miller (Cruise).  Her run-in with Miller puts her on the radar of the the bad guys—a traitorous CIA Agent Peter Sarsgaard) and an arms dealer (Jordi Mollà)—who want to capture Roy because he's protecting a battery that could power a small city.  They believe poor June is either a covert agent working with Miller or an unfortunate civilian who needs to be "dealt with" regardless.  Once June discovers the severity of her predicament, the film wastes time having her repeatedly run away from Roy even though it's clear he's the only one who can protect her.  Her futile escape attempts only serve to make the character seem life a shrill doofus although Diaz does her best to make June sympathetic.

Eventually, June comes to her senses and joins Roy on his journey.  Well, "join" may not be the best term.  June is knocked out five times during the course of the movie, four of those times by Roy because she's essentially baggage that has to be carted around.  The first time it's a sensible plot decision.  The second time leads to a fun montage where we see her briefly awakening to find her and Roy in some insane predicament before blacking out again.  Then it just gets sad, not because of Roy's behavior, but because the film can't think of a way to keep her as comic relief and provide character development.

Luckily, while June is a mess for most of the movie (and when she does change, it's like a switch is flipped), Roy is an absolute delight.  Cruise elevates Knight and Day from an irritating movie to an acceptable piece of summer action-adventure fluff.  Even though Roy is a ruthlessly efficient and dangerous operative, he's the most polite ruthlessly efficient and dangerous operative you'll ever meet.  It's a fun character and Cruise's performance is the film's greatest strength.  He also plays well off of Diaz, but the relationship would work better if June wasn't such a chore and he didn't render her unconscious four times (he's not responsible for the fifth knockout).

The movie attempts to match Cruise's affability by pulling off the tricky balance of being self-aware without falling into self-satisfied irony.  Knight and Day knows it's an action-comedy, but rather than break the fourth wall, it makes the safe assumption that you understand the tropes of the genre and that's why you enjoy it.  We all know that the bad guys can fire endlessly at the heroes and never hit them once, so why not have Diaz run out into the open when she's surrounded by black-ops commandos?  It's better to just make an exciting action scene, and embrace the silliness.  It's a difficult feat but Mangold manages to pull it off.  Knight and Day is in on the joke, but it's laughing with the genre rather than it.

Sadly, this likability is undermined by the weak characterization of June.  She comes into her own in the third act, but the shift is too sudden and by then the film is already running too long. Furthermore, the movie is almost two hours when it could have easily been a brisk ninety minutes.  It's not like any of the other actors have much to do and the plot isn't some intricate house of cards.  Cruise and Mangold give the film as much energy as possible and Diaz fights a losing battle, but eventually the faults begin to outdo the movie's strengths.  Maybe next time it'd be better to drug the female protagonist no more than three times.

Rating: C+