What “Murder By Numbers” does for the thriller genre, Sandra Bullock does for her career. No longer the girl next door, Bullock plays a no-nonsense but emotionally charged and sexually voracious cop – all while keeping her shirt on.

“Murder By Numbers” reverses the typical thriller plot scheme by letting us know who did it from the beginning, keeping the reasons why and how at arms length. Although we can make an early estimate of why the crime was committed, director Barbet Schroeder does a good job of keeping the evidence hidden. However, just as we’re enjoying a new narrative structure and a changed leading lady, convention creeps in, establishing no further plot twists, or clever escapes that could have kept this film fresh and vibrant.

Ryan Gosling (Richard) and Michael Pitt (Justin) play two disaffected high school students bored with life and themselves. Their solution to an ideal life of caviar appetizers and absent parents is to commit the perfect murder. But to everyone around them, they appear to be not only opposites but also natural enemies. Richard is good-looking and suave, but arrogant and condescending. Justin, on the other hand, is a shy genius, able to juggle the sciences and Nietzschean power theories. Together they kill a random woman and simply leave her to be found. As Richard puts it, “We’ll just watch the cops do their job.”

Cassie Mayweather (Bullock) is a detective with a past. She works on hunches, not facts, and, as word has it, sleeps with all of her new partners. She’s a firecracker on the job, is disliked by her coworkers, and chases shots with beer. But her character never develops as well as the two students she’s trying nail. Until her past is revealed in a crammed confessional, she rarely gives convincing motivation for her gruff sensibilities and subjective charge. She’s a victim determined to stop other victims, but Bullock fails to portray someone who’s really working from experience.

“Murder By Numbers” works the role reversals. Cassie kicks reluctant lover Sam Kennedy (Ben Chaplin) out of bed. She is the one who doesn’t want any commitment. The homoerotic relationship between Richard and Justin is subtle and somewhat convincing – if killing someone doesn’t bring two men closer together, what does? Lisa, the innocent schoolgirl who can’t help but be seduced by her two contemporaries’ charms, ends up causing a schism between Justin and Richard. The formula works, and the girl is the center of the murderers’ problems – in fact, it’s Lisa who really puts the case to a close.

Schroeder divulges information at the right time, keeps us perilously confused over the convoluted scheme, and does his best to keep us doing a double take on the events unfolding. But there’s a lack of bloodlust and trauma that essentially creates a sterile, “anyone can do it” attitude toward slaughtering a random housewife. Hey, why not?