Some people, astoundingly, will not know how Agatha Christie’s famed story about a snowbound luxury train, a murdered passenger, and a dozen suspects turns out. Most, however, will.

But there’s a mystery within this mystery: It’s adapted from one of literature’s most famous whodunits, features an all-star, A-list cast (see the ads), and employs today’s most advanced, whiz-bang filmmaking techniques. But it’s somehow too busy looking great to ever generate any real momentum, tension, emotion or excitement. (I’m trying really hard here to eschew clever train-related jokes.)

The consensus on this remake, in a word, is “unnecessary,” especially in light of Sidney Lumet’s still-rentable and far better 1974 version starring Albert Finney, Lauren Bacall and Ingrid Bergman.

Director Kenneth Branagh casts himself as the Belgian super-detective with the elaborate face furniture, and he’s diverting. But I somehow doubt Agatha ever envisioned Hercule Poirot as a gun-toting action hero.

It’s not terrible (well, except for that laughable last act), and better on average than most of what’s out there in the multiplex right now, but hardly a must-see. (114 min)