Aboard the speeding locomotive of “Bullet Train” ride at least five assassins, one venomous reptile (a snake on the train), countless glib Guy Ritchie-esque slo-mo action sequences, and one bucket-hat wearing Brad Pitt.

It’s a lot of ingredients that go into this candy-colored, battle royale of a movie. But the only one that really matters is that last one. At 58, Pitt’s star power has never seemed so easy and so natural. Radiant in “Once Upon a Time… in Hollywood,” delicious in “The Lost City,” Pitt glides into “Bullet Train” in an rarified state of cruise control. Seldom has a movie star seemed to be having so much fun.

In “Bullet Train,” which opened in theaters Friday, Pitt plays a hired gun by profession but little else. His code name is Ladybug. He doesn’t like guns. And in his first job back after a hiatus of self-reflection and therapy, he goes into lethal fights with great reluctance, spouting self-help slogans like “Hurt people hurt people” in the midst of hand-to-hand combat. Pitt, a maximum movie star with a minimalist bent, is a hitman with no taste for hitting.

Ladybug, tasked to grab a very particular briefcase off a train headed from Tokyo to Kyoto, might not be up for the job, but the bigger question is whether “Bullet Train” is a good enough vehicle for its biggest star. Director David Leitch, the stuntman-turned-director of “Atomic Blonde” and “Deadpool 2,” has brought the style and energy of a “John Wick” film (he co-directed the first) to a setting that has traditionally been associated with more subtle methods of killing.

In “Bullet Train,” a movie that proudly opts for style over substance, characters are introduced like videogame fighters, running gags get run into the ground and a winking irreverence lands somewhere in between playful and exhausting.

“Bullet Train,” a Columbia Pictures release, is rated R by the Motion Picture Association of America for strong and bloody violence, pervasive language, and brief sexuality. Running time: 126 minutes. Two and a half stars out of four.