‘Mortal Engines’ a special-effects sci-fi outing of the YA kind

We never fully know what happened in the Sixty-Minute War that devastated the Earth prior to the events of “Mortal Engines.” Whatever it was, it has a catchy name. And it created a whopper of a dramatic premise.

If you can swallow that premise, maybe you’ll find “Mortal Engines,” a special-effects-heavy sci-fi outing, passable entertainment. But, oh, what a concept.

The Earth is now dotted with mobile cities, which roll across continents leaving humungous tire treads and massive destruction. The only way these cities survive is to devour other, smaller towns. It’s kind of like applying Darwin to the Transformers.

“Mortal Engines” comes from Young Adult novelist Philip Reeve, by way of the “Lord of the Rings” creative team Peter Jackson, Fran Walsh and Philippa Boyens, who wrote and produced the film. Jackson didn’t direct this one — that credit goes to visual effects maestro Christian Rivers — but you sense maybe he was looking over the director’s shoulder at key moments.

The generic characters include a disfigured but determined heroine (Hera Hilmar) who teams up with a goofy young historian (the likable Robert Sheehan, who was also in a YA franchise movie called “The Mortal Instruments,” so try to keep this all straight). They’re cast out of the gargantuan traveling city called London, at the whim of powerful chief historian Thaddeus Valentine (the great Aussie actor Hugo Weaving, from “LOTR” and the “Matrix” movies).

You know how devious historians can be, and Valentine has a plot to rule the world. But our heroes and their new allies might stop him — if they aren’t slaughtered by a fearsome half-robot named Shrike.

Shrike, a motion-capture entity given life by “Avatar” bad guy Stephen Lang, is one of the hipper things about “Mortal Engines.” When he strides into a room with a low ceiling he doesn’t duck his head — he just crashes his noggin right through the rafters.

The other standout character is Anna Fang, played by singer-songwriter Jihae in a breakout performance of such utter drop-dead coolness it should be a major launching pad. Fang pilots a butterfly-shaped airship straight out of Jules Verne, one of the film’s many gaudy steampunk touches.

There’s a lot to look at here, but not much to think about. The story beats are so broad and the characters so bland that this movie wears you out well before the big finish, despite the quirky touches.

The box office is littered with attempts to fire up new YA franchises — let me know if you hear anything about a sequel to “The Mortal Instruments,” which came out in 2013. Maybe Peter Jackson’s reputation can carry “Mortal Engines” to success. If not, let’s get some other vehicle for the adventures of Anna Fang, and make it soon.

“Mortal Engines” (2½ stars)

Peter Jackson produced this adaptation of a post-apocalyptic Young Adult novel, set in a landscape where giant cities move around devouring smaller towns. Huh? If you can swallow that premise, there’s some steampunk appeal in this film’s design, although the plot beats are predictable and most of the characters generic.

Rating: PG-13, for violence

Opening: Alderwood, Alderwood Mall, Everett Stadium, Galaxy Monroe, Marysville, Olympic Theater, Crest Cinema, Thornton Place Stadium, Woodinville, Cascade Mall