OFF THE RAILS

Agatha Christie was the master of the whodunit and to whom. One of her best-known works is “Murder on the Orient Express” and for good reason (check out the 1974 version directed by Sidney Lumet and starring Albert Finney and not the 2017 misfire directed by Kenneth Branagh). The identity of the killer is revealed slowly, like Christie is peeling the layers of an inscrutable onion.

So now we have “Bullet Train,” closer to “Snowpiercer” in terms of murder and unbridled mayhem than anything Christie could dream up, and that’s not all bad.

Brad Pitt is the bleeding heart and soul of “Bullet Train,” a contract killer who’s been brought back from retirement and saddled by his handler with the unfortunate code name Ladybug. She says it’s because a ladybug is the symbol for luck. But in his line of work, he thinks that’s a stretch.

His assignment is to pinch-hit for a mercenary colleague named Mr. Carver, revealed much later as a Hollywood heavyweight but his identity isn’t too much of a surprise if you’ve been following the career of director David Leitch (“Deadpool 2”).

Ladybug is to recover a briefcase aboard the world’s fastest super train that’s en route to Kyoto from Tokyo. Find it and get off, he’s told. But easier said than done.

Because others are after that same briefcase and its contents, which eventually we learn is a boatload of cash and gold bullion.

Soon, though, we find that the briefcase is in the hands of brothers with code names Lemon and Tangerine, played by Brian Tyree Henry and Aaron Taylor-Johnson. Given that Lemon is Black and Tangerine is white, the brother thing is just one more joke among many here.

They are also guarding the son of a Russian super villain with the spine-chilling sobriquet White Death. And they are under orders to deliver both the son and the loot or suffer the consequences. Super villains can be downright ornery when their orders aren’t followed and White Death is notoriously vengeful.

But Ladybug gets lucky and finds the briefcase and even uses it to fight off an assassin named Wolf, whose wedding reception Pitt’s character is shown to have disrupted in a telling flashback. Or did he?

Yes, there are so many villains aboard the train, you almost need a scorecard. But director Leitch finds a clever way to keep it all straight.

In a bucket hat and black-rimmed glasses, Pitt exudes a chill A-list charm, tossing out asides like small hand grenades and demonstrating he’s every bit an action hero, even at this stage of his career. And crucial to the story is that Ladybug refuses to carry a gun, so he resorts to dispatchings that a MacGyver might envy.

But make no mistake. This is a gorefest that more than earns its R rating, with impalings, beheadings and any number of unfortunate events. Some even touching and sad. And perhaps one of the reasons that “Bullet Train” is so watchable is that gunplay often takes a back seat to swordplay, an obvious nod to the samurai culture that colors Japan’s early history.

Pitt is helped along with occasional cameos by some A-list friends, one of which had me laughing out loud. Their contributions, though, seem appropriate for an action flick in which bodies pile up like cord wood but that doesn’t take itself too seriously.

If you have a yen for excitement, this is just the ticket.