Had “American Assassin” been made twenty or thirty years ago, the villains would have been of different national origin, and the star would have been a beefy fellow like Arnold Schwarzenegger or Sylvester Stallone rather than a trim young dude like Dylan O’Brien, but the basic plot outline would have been the same. Despite the updating, the movie is essentially a boilerplate action flick following a template that hasn’t changed much for decades, and while efficiently made, it holds no surprises.

O’Brien, who began his career as a sidekick on MTV’s “Teen Wolf” and then took on the lead in the “Maze Runner” franchise, stars as Mitch Rapp, a young American wounded by gun-wielding Libyan terrorists at a resort on Ibiza; their vicious leader Mansur (Shahid Ahmed) takes particular pleasure in killing Katrina (Charlotte Vega), the girlfriend to whom Mitch has just proposed. Single-mindedly determined to avenge her death, Rapp devotes his days to becoming a martial-arts killing machine and learning Arabic to contact Mansur’s group online and offer his services as a warrior. (His commitment is shown by the fact that he neglects to shave, winding up with a thick black beard.) He is finally successful in getting invited to the villains’ lair, but before he can take his vengeance, U.S. special forces intervene to slaughter the cell. It seems the CIA has been following Rapp’s e-mail and tracked him to the group’s hideout.

The question now is what to do with the self-trained vigilante. The Agency’s Deputy Director, Irene Kennedy (Sanaa Lathan), sees him as a potential recruit for their black ops force, and despite doubts by Director Stansfield (David Suchet), she’s allowed to place him with hard-boiled field operative Stan Hurley (Michael Keaton) in his remote camp. After some rather cursory training, Rapp is picked by Stan, along with fellow trainee Victor, to join him on a mission to track down a stolen shipment of plutonium and a mysterious key (the plot’s MacGuffin) that will allow it to be used as a thermonuclear device. The job will take them to Turkey, where they will join beautiful long-time operative Annika (Shiva Negar) to deal with the arms dealer planning to sell the items to some shadowy buyers, who just might be connected to a trio of Iranian officials (Mohammad Bahri, Navid Negahban and Joseph Long).

In the ensuing mayhem—which takes the team from Anatolia to Rome—Rapp proves to be a loose cannon who disobeys orders. But wouldn’t you know it, his insubordination always bears a beneficial result. As to the villains, it turns out there are good Iranians (those who support the nuclear treaty) and bad ones (those who don’t), but the ultimate bad guy is an American, once Hurley’s top protégé whom Stan left behind after a botched job and was presumed dead. “The Ghost,” as he’s called, is played by Taylor Kitsch and is mighty miffed that his mentor abandoned him.

Among the delights that “American Assassin” has in store in the later reels are double-crosses, an extended fight in a hotel suite, the near-fatal bathtub drowning of a suspected traitor, a protracted torture scene with fingernails in jeopardy, a car chase, an encounter with some vicious dogs, a one-on-one with a brute in a fancy penthouse, a fistfight aboard an out-of-control speedboat, a helicopter rescue and—just to top it all off—a nuclear explosion at sea than threatens to destroy the entire Sixth Fleet. But not to worry: the world is saved.

Michael Cuesta, whose earlier work had a much more cerebral slant (check out his debut film, the remarkable “L.I.E.,” which also featured Paul Dano in his first major role), manages the action efficiently enough—with the help, no doubt, of cinematographer Enrique Chediak, editor Conrad Buff IV, and what must have been a small army of stunt coordinators and stuntmen, as well as a substantial visual effects staff. His work with the actors, on the other hand, shows little of the sensitivity he’s exhibited in the past. But characters like Rapp, Hurley and Ghost are intended to be big, broad types, and O’Brien, Keaton and Kitsch respond accordingly. As for the other villains and red herrings, they serve their purposes in the elaborate cross-global board game that’s not challenging enough to be compared to chess. Checkers is more like it.

Come to think of it, “American Assassin” doesn’t seem like a modern equivalent of a Schwarzenegger or Stallone blockbuster from the distant past, but of their chintzier cousins—like the “American Ninja” movies with low-rent replacement Michael Dudikoff. It’s worth remembering that the movie is based on one of a series of books about Mitch Rapp by Vince Flynn, and could spawn a series of its own. Maybe we’ll be watching Dylan grow for some time in this role; if so, let’s hope the future scripts mature with him.