I don't know if they still do this or not, but back in the day, cartoons would suggest the eternal battle of good vs. bad by placing an angel over a character's shoulder, and a devil over the other one. Both would attempt, by various means, to persuade the mortal to follow their advice about how to proceed.
In the live action film "Mr. Brooks," there is no angel character balancing the moral dilemma facing the title character. He's the Portland businessman of the year, a husband and father who runs a box manufacturing company. As portrayed by Kevin Costner, he seems like a good guy, although he proclaims at an AA meeting that he too is an addict.
Of course, he doesn't say to what he's addicted, and that turns out to be killing. Like most addicts, he knows what he's doing is wrong, but he can't help it, especially when the devil figuratively and literally over his shoulder comes in the form of William Hurt. His character doesn't really exist, at least to anyone but Mr. Brooks, but he's always there in pure id form, constantly egging on the protagonist to do the wrong things, specifically those that give him (both Brooks and "Marshall") basic pleasure.
With his over the shoulder help, Brooks is quite good at what he does. In professional circles, he's known as "The Fingerprint Killer," and the cop character played by Demi Moore isn't any closer to catching him than she was when he last struck two years ago. In true movie form, she's also beset by her own demons, namely that of trying to prove she's worthy despite being wealthy (the usual dad/daughter issue) while dealing with a soon-to-be ex-husband who keeps upping his divorce price.
Despite or because of his extracurricular activities -- that he keeps secret from his wife (Marg Helgenberger) by repeatedly telling her he's out back with his pottery kiln of all things -- he's worried that his college freshman daughter (Danielle Panabaker) might be a chip off the old block when she unexpectedly returns home amidst some criminal doings back at school.
Then there's "Mr. Smith," an otherwise regular guy who just so happens to photograph Brooks in the act of giving new and deadly meaning to the term coitus interruptus. Smith plans to blackmail the killer, but not for money. Instead, having gotten his voyeuristic thrills via photographing the nightly, open-curtain carnal sessions, Dane Cook's character wants to up the personal rush ante by tagging along for the next kill.
That's the setup for this would-be psychological thriller that certainly isn't lacking for potential, particularly regarding the abundant subplots. Yet, despite all of that, it's not terribly thrilling, and while it isn't simply terrible (to the point of being a true guilty pleasure or something of a cartoon itself), it's clearly not as good, interesting or engaging as it could and should have been.
More movie star than thespian, Costner is an interesting choice to play the dual personality. Far better in certain roles than others, he just isn't that believable here, no matter how hard he tries to look intense and/or conflicted and troubled by his moral quandary. His best scenes are those where he plays off Hurt's devil-over-the-shoulder character, simply because the latter seems to be truly enjoying chewing on the scenery.
While Cook is believable as the voyeur, he isn't that interesting and certainly not likable. Oddly, Helgenberger's character isn't around much, which nevertheless doesn't help the incredible issues of her not realizing that when Earl says "kiln" he's really saying "killin.'" It would have been far more interesting (and presumably more suspenseful) had she sniffed out the truth and thus potentially endangered herself. Throw in the potentially homicidal teenage daughter, and that could have created a "fun" family dynamic.
Ruben Santiago-Hudson isn't allowed to do much as a secondary cop character, but maybe he simply wanted to distance himself from what can best politely be described as a rough performance by Moore. Saddled with too many subplots revolving around her (beyond the daddy and divorce issues, a killer she put away in the past has also escaped and is now after her), the actress is never believable in the part, and like the rest of the characters, isn't engaging or likable.
And that's where writer/director Bruce A. Evans and co-writer Raynold Gideon end up disappointing the most, particularly regarding the protagonist. Here we have an obviously troubled and delusional character, but the filmmakers never delve deep enough into his persona to make him as interesting or compelling as he might have been. With no emotional hook for the viewer, we simply watch the many story mechanisms at work.
Coupled with some plot developments that aren't smart enough and/or believable (the biggest being the otherwise perfectly meticulous killer not realizing the nearby curtains are obviously open during the pivotal nighttime double-homicide, and there are many others), the film might look good and feature a decent name cast, but it just isn't that thrilling. And that's a significant problem for a would-be thriller like this. "Mr. Brooks" rates as a 4 out of 10.