It seems that at least once a month we’re confronted by yet another adaptation of a young adult novel about a dystopian future that also happens to be the first part of a trilogy. “The Maze Runner” follows the usual pattern: it introduces a heroic teen and puts him (or her) through a series of challenges that prove the protagonist’s mettle. But though the movie ends with triumph, the victory is incomplete and will require further installments to achieve full resolution. Wes Ball’s debut feature is even more blatant than most in forecasting a sequel; it’s literally like the first chapter in an old forties serial, though far longer and with much improved production values.

The story centers on a group of male teens who have been deposited, one by one, by some unknown force for an equally unknown reason in a forest glade, beside which is situated a huge maze that represents the only mode of escape. Unfortunately, the opening to the labyrinth closes at sundown and the gigantic inner walls shift position each night; and anyone trapped inside after the closure will become prey to the so-called Grievers, huge spider-like creatures with a nasty attitude toward interlopers.

The newest arrival, sent via a cage among regular supplies on a clattery elevator, is Thomas (Dylan O’Brien), who can’t remember his name or his past—a common but temporary phenomenon, he’s told by the other lost boys. Welcomed by some—like Alby (Aml Ameen, the leader of the Gladers, and his lieutenant Newt (Thomas Brodie-Sangster), as well as chubby Chuck (Blake Cooper)—Thomas earns the instant enmity of Gally (Will Poulter), who believes that the group’s only safety lies in obedience to the established rules and sees in the newcomer’s rebelliousness a danger to them all. The only other Glader of special importance is Minho (Ki Hong Lee), the leader of the elite Runners, who venture into the maze each day to map out its inner workings. It’s a dangerous job, of course, because getting trapped inside would mean almost certain death.

The basic narrative thrust of “The Maze Runner” is on how Thomas becomes the focal point of a movement to liberate the boys from the trap they’ve been put into, largely by joining Minho in his quest to figure out the maze. His emergence as the “chosen one” who will figure the way out is made difficult not only by Gally’s opposition, but by the arrival of the glade’s first female—Teresa (Kaya Scodelario), whose recognition of Thomas encourages suspicion, not least in Gally, that more is going on here than meets the eye. And that suspicion turns out to be correct, as becomes semi-clear with the entrance of enigmatic scientist Ava Paige (Patricia Clarkson), who haunts Thomas’ memories mouthing the refrain “WCKD is good.” Now whatever could that mean?

We learn the answer to that question—or a partial one, at least—as the movie concludes, but the ending, like that of the original “Star Wars,” leaves a lot dangling to await further installments. Mention of George Lucas’ sci-fi romp should not, however, be taken to suggest that “The Maze Runner” is at all on the same level. As far as these sorts of pictures go, it’s not terrible—neither as good as “The Hunger Games” nor as bad as “The Giver.” But it’s nothing special, either.

The young cast is for the most part an agreeable bunch: O’Brien, who cut his teeth on MTV’s “Teen Wolf,” and Scodelario, who was in the original British version of “Skins,” go through their paces efficiently enough, and though Poulter is stuck in a one-note angry-young-man persona that doesn’t give him room to build on what he managed in “Son of Rambow” and “We’re the Millers,” he does what the role demands of him well enough. Among the supporting Gladers, Brodie-Sangster and Ameen are notable for their amiability and Lee for his physical chops. As for Clarkson, she fulfills pretty much the same function here that Meryl Streep did in “The Giver,” Glenn Close did in “Guardians of the Galaxy” and Kate Winslet did in “Divergent.” They’re all required merely to be present rather than to act. On the technical side, this is a pretty proficient piece of work, with Mark Fischella’s production design and Enrique Chediak’s cinematography emphasizing grittiness over flash, and—compared to other movies in this genre—a relatively sparing use of special effects, the maze and Grievers aside. The decision not to shoot in 3D is a welcome one, especially given the natural darkness of many of the scenes, which would have been exaggerated by the format.

“The Maze Runner” doesn’t exactly sprint—it goes on for nearly two hours, and often slows down for what seems like an overextended breather. But though hardly a champion-quality entrant in this crowded YA field, it crosses the finish line winded but game, and will probably make it to the next race, unlike many of its rivals.