I count two movies in Murder by Numbers, the newest Sandra Bullock vehicle in which the star appears to be tough and tomboyish, but reveals herself to be soft and all-girl when the right guy gets past her pj's. First, of course, what we've got here is a standard Sandra Bullock vehicle: The dark-eyed sport plays a homicide detective who demonstrates she's one of the guys the same way she did in ''Miss Congeniality'' -- i.e., by eating and drinking with a gusto just this side of barnyard.
As Cassie Mayweather, Bullock is a California cop who's allergic to romance, but who has no trouble seducing a man, and then kicking him out of bed when she's ready for serious sleep. Cassie's newest working partner (and bedmate), the smart and presentable Sam (Ben Chaplin), finds this out early on, leading us not at all subtly to suspect that something as yet unrevealed in Cassie's personal history makes her shut down and fill up with liquor. Unfortunately, what we also realize is that there's going to be no way to avoid finding out what that secret sorrow is in the last act -- however little we care -- since we know even before the lights go down that a Sandra Bullock heroine not only will survive, but will also clean up nicely and Feel the Love.
But ''Murder by Numbers'' is also a dirtier, darker crime thriller about a couple of cocky high school seniors who pride themselves on their ability to commit the perfect murder -- a compulsion that continues to inspire movie plots long after the notorious, real-life 1924 case of the calculating college-age killers Leopold and Loeb. Brilliant outcast Justin (Michael Pitt, the baby-faced beauty who broke a transsexual's heart in ''Hedwig and the Angry Inch'') bonds with popular, nihilistic Richard (''The Believer'''s Ryan Gosling, a phenomenal talent even in junk like this), founding a club of two on the boredom and neglect of affluent adolescence. And they might just get away with their scheme -- Chris Penn plays the hapless school janitor ensnared in their booby trap of misleading clues -- were Cassie not so particularly on guard, for reasons of her own, against the lies of privileged young men. ''Do you get away with this s--- because you look like that?'' she asks a smirking Richard, speaking the pointed, sour dialogue of Tony Gayton's screenplay.
The relationship between the twisted killers in ''Murder by Numbers'' is far more interesting than that of the collaborative cops, not only to us, but also to director Barbet Schroeder -- a fancier of the underbelly in ''Reversal of Fortune,'' ''Barfly,'' and ''Single White Female,'' and a guy who really couldn't give a fig what Sandra Bullock does in her pj's. With the deceptively warm light of master cinematographer Luciano Tovoli (''The Passenger'') beaming down on them, Pitt and Gosling clash and embrace in such psychosexually charged performances that even though Bullock engages in a climactic scene of blue-screen peril, she essentially cedes the match to the kids. In this mediocre murder case, their presence is the only thing that's really killer.