In the mystery thriller Law Abiding Citizen, a man begins killing off members of the justice system whom he feels were too lenient in prosecuting the two thugs who killed his wife and young daughter 10 years earlier.

Law Abiding Citizen is more than just another Death Wish vigilante movie. It keeps one guessing until nearly the end. And that’s not only because of the clever and startling ways one-man assassination squad Clyde Shelton (Gerard Butler) carries out the murders (there’s one moment where the entire preview audience jumped out of their seats in shock), but for the fact that Clyde has been locked up in a prison cell while the very public and grisly murders are unfolding. No wonder the mayor of Philadelphia (a svelte Viola Davis, once of Central Falls) is frustrated and angry.

It’s unfortunate that Law Abiding Citizen stumbles in the end when we learn the very improbable way that Clyde has been able to accomplish his seemingly magical murder spree, something that depends on a lot of unrelated elements falling into place in a very precise way. But, until then, Kurt Wimmer’s script springs enough jolts and surprises to keep one invested in its story.

Director F. Gary Gray, who directed Mark Wahlberg’s The Italian Job in 2003 and has done many music videos for the likes of R. Kelly and Ice Cube, gets the adrenaline pumping right from the start with the horrific murders of Clyde’s wife and daughter (although the child’s death is thankfully left up to the imagination). We next find Clyde 10 years later with red-rimmed eyes and a haunted look as he learns that the real killer has been set free after serving a short sentence and only his accomplice is to die by lethal injection.

By presenting the killer as a sadistic creep, Wimmer and Gray set us up to back Clyde in his vigilantism. Even prosecuting attorney Nick Rice (Jamie Foxx) whispers to Clyde that he applauds the blood-splattering way — which we are privy to in a gruesome nod to the Saw movies — that he rid the world of this monster. Surprisingly, Clyde confesses to the gruesome murder and is locked up.

But then the real killing begins as one by one the lawyers and judges involved in the case are eliminated in shocking and clever ways. Everyone suspects Clyde of being the mastermind behind the mayhem. And yet, how does he do it? The killings are carried out over several days and require elaborate set ups. But without access to an accomplice, how is it possible?

Trying to figure this out is more than half the fun of Law Abiding Citizen, which has a solid cast (Foxx won the 2004 best actor Oscar for Ray, Davis was nominated this year for Doubt, and Butler has been hot since 300 in 2006, although he hasn’t come up with as big a hit since) working in what is essentially B-movie territory. It’s all two-dimensional characters and situations, although the high-powered cast manages to give the film some depth and intensity.

Gray builds up the shocks so that we are almost, but not quite prepared for what he’s about to spring. Amusingly, he crosscuts between a death row execution and scenes of Rice’s young daughter giving a cello recital at school.

Although Law Abiding Citizen’s resolution is far-fetched, there are times when it will keep you on the edge of your seat.

***Law Abiding Citizen

Starring: Jamie Foxx, Gerard Butler, Colm Meaney, Bruce McGill, Leslie Bibb, Regina Hall, Emerald-Angel Young, Christian Stolte, Viola Davis.

Rated: R, contains gruesome violence, torture, profanity, sexuality, nudity.

mjanuson@projo.com