The first 20 minutes of Christian Rivers' otherwise dreary Mortal Engines stand as a perfect illustration of the logic behind buying subscription passes to your local multiplex: By all means, go watch the opening on the biggest screen possible if you have any interest in beholding a chase scene between great cities built atop colossal tank-treaded vehicles. Then maybe go about your day.
Yes, there are mobile cities eating each other: The sequence finds horizon-wide London, its skyline as jumbled up with landmarks as the roof of Las Vegas' New York-New York casino, stalking a much smaller Balkan town across the steppes. The camera swoops around the impossible combatants, showing us complex action with clarity and verve. Imagine the white city from the third Lord of the Rings movie gone steampunk and roving the landscape like an angry Pac-Man -- this stuff is wonderfully weird and expertly rendered. (Peter Jackson is a producer, and he cowrote the script with his Rings and Hobbit partners Fran Walsh and Philippa Boyens.)
What follows that spectacular start is a confused, clanging film too rushed to invest emotion into. It answers a complaint many viewers had about Jackson's second and third Hobbit movies but does so the wrong way: Rather than three hours of aimless action and little story, Mortal Engines runs just over two -- but the proportions of action to story are still out of whack. The film plays as if a three-hour epic has been sliced down to size in the editing, but only the scenes establishing character and context have been cut. It lurches too abruptly from from set piece to set piece to make the basics clear.