Those who felt their loyalty tested during the fifth installment of Lionsgate’s Saw series can now rest easy. Director Kevin Greutert isn’t playing games. Saw 6 not only stands alone as an exceptional white-knuckle horror film, it truly rewards fans of the series by providing further insight into their beloved anti-heroes and by revealing jaw-dropping twists that will blow even the most die-hard away.

Saw 6 finds former civil engineer turned “Jigsaw Killer” John Kramer (the great Tobin Bell) posthumously tormenting the morally-challenged employees of a major health insurance provider. William (Peter Outerbridge), the company’s slick CEO, is the man responsible for denying Kramer’s request for an experimental cancer treatment that could have saved his life. Not surprisingly, the heartless suit takes center stage in Kramer’s game.

While most non-horror movie critics will scoff at Saw 6’s stab at political commentary, those of us who don’t need to stare at Sean Penn’s (Milk) weepy face for three hours to appreciate a message film can get caught up in the ultimate HMO revenge fantasy that follows (I saw the movie twice during its opening weekend for its therapeutic value alone).

Which brings us to the traps.

Saw 6 features some disturbingly wonderful contraptions, the most intense of which is the “carousel.” William’s “dog pit” of actuaries find themselves strapped onto a spinning carousel that is rigged to a shotgun set to blast them one at a time. William can only save two of the six people by pressing a fail-safe button that triggers a drill into his hand.

The folks on the carousel plead desperately for their lives (I’m pregnant!) and throw each other under the bus (“No, she’s not! She’s fucking lying!”). It’s a gruesome scene that works both the nerves and funny bone.

Of course, the real trappings to a Saw film lie in its mythos. The movies are meant to be viewed as a whole, each installment a piece to a bigger story (not unlike “Lost” and other works that develop an intricate mythology). Writers Marcus Dunstan and Patrick Melton do an exceptional job of enhancing the Saw backstory. The duo joined the franchise in 2007, stepping in for original series writer Leigh Whannell. After a shaky start on Saw 4, they showed promise in part five when they fleshed out the relationship between Kramer and the detective Hoffman character.

Costas Mandylor (who up until now I had only enjoyed on David Kelly’s 1992 TV serial “Picket Fences”) really captivates in this entry as hardboiled detective Hoffman, Jigsaw’s morally-compromised successor. Watching Hoffman continue to scramble for a chance to reclaim his life after Kramer’s death is nail-biting good stuff. His final confrontation with Kramer’s wife (Betsy Russell) is a scene stealing surprise that will pump up fans for part seven. However, it’s Shawnee Smith’s much welcomed return as homicidal hottie Amanda that delivers the film’s biggest “Oh, shit!” revelation.

Saw 6 is in theaters now.

• Movie Homepage: Saw 6 Official Homepage