“The 5th Wave” is yet another teen dystopian novel adaptation hitting theaters, adding to the genre glut where young people have to fight for freedom and save the world.

This entry — based on the best-selling book of the same name by Rick Yancey, the first in a trilogy — is perhaps the most sedate one, vastly easier to follow than series like “The Hunger Games” and “Divergent,” where there is a monstrous alternate world with gibberish names and dense, contrived plot lines that are better conveyed through prose.

Chloe Grace Moretz stars as Cassie Sullivan, a survivor in a world hit by four waves of alien attacks. A menacing, silent spaceship lurks in the sky. Like modern-day biblical plagues, it begins with an electromagnetic pulse that shuts down all electricity. Then come the earthquakes, flooding and disease. Millions are dead.

Cassie, with her dad (Ron Livingston) and younger brother Sammy (Zackary Arthur, “Transparent”), trek from their home to a refugee camp. A massive dust cloud and the grunts of military vehicles break the monotony of the farming community when saviors arrive in the form of Colonel Vosch (Liev Schreiber) and his soldiers, who whisk away the children to safety.

But can they be trusted? Can anybody? The aliens can be anyone, and it’s impossible to know who is still human.

When Vosch takes Cassie’s brother, much of the film is her struggle to reunite with him. Along the way, she is helped by the mysterious Evan Walker (Alex Roe, who clumsily delivers the film’s most groan-worthy lines).

Meanwhile, Sammy and the other taken kids — who include Ben Parish (Nick Robinson, “Jurassic World”), Cassie’s high school crush — are being trained as child soldiers to fight the aliens.

“The 5th Wave” can be powerful at times. From the start it offers some bold visuals, from crashing planes to horrific tidal waves, coupled with tense character moments. When Cassie finds an injured survivor with his hand under his jacket, it’s unclear if he’s stopping bleeding or holding a gun. Trust is out the door in this new landscape. It’s a powerful scene with a powerful outcome, but it’s a rarity here.

Instead, what you mostly get is a lot of running through the woods, action sequences and discussions about trust and what it means to be human. The film takes its time as it builds to its conclusion, but then rushes to an ending filled with convenient events to bring the characters together.

Of course, this is just the first book of a trilogy, so the ending doesn’t feel final. Time and box-office numbers will decide if the story continues on the big screen. Who knows? This is by definition an OK movie. It’s fine. But the book is quite good, so if you’re at all intrigued, get reading instead.