Five people wake up in a mysterious room chained to a wall full of spinning blades. Such a grisly start to a film can only mean one thing: After a seven-year absence, the Saw franchise is back. Don’t expect the break to have changed the formula: This return, centered vaguely on the villain Jigsaw ( Tobin Bell), finds these victims forced to make sacrifices of (literally) life and limb in order to save themselves. The torture sequences, which on occasion offer compelling moral quandaries, are not the worst parts, however. That distinction would apply to the scenes in which the police attempt to capture Jigsaw. With the film’s crude staging, dialogue out of Law and Order’s waste bin, and a lazy mystery, the gruesome torture can feel like a reprieve. Jigsaw is not even slightly scary; the main emotional reactions it evokes are boredom and, ultimately, depression. Rated R. 91 minutes. Regal Stadium 14.