Featuring the voices of Anna Paquin, Alfred Molina, and Patrick Stewart. Rated PG.

Where American animators can barely manage to top 90 minutes in their super-expensive medium, Japanimé masters somehow manage to crank out two-hour epics every few years. Granted, there's often a lot less going on in any given frame of manga-derived art: those goggle-eyed warriors are often as stiff as Hiroshige block prints. But they also tend to be filled with the kind of mysterious atmospheres and metaphysical arguments that would drive Disney executives under their desks.

Certainly, there's no lack of ambition in Steamboy, a long-awaited effort from Katsuhiro Otomo, the fellow who brought us Akira, one of the most influential of all Japanese 'toons. But somewhere along the way, Otomo seems to have got lost in his own labyrinthine creation. As it drags on through a laboured last quarter, mostly set in the claustrophobic confines of the not very interesting "steam castle", the movie turns into much less than the sum of its parts.

It's been 16 years since Akira helped animé burst out of the for-cultists-only closet, and roughly half of those years was spent developing this, reportedly the most expensive Japanese animation ever. Perhaps Otomo should have used a little more of that time getting a really good script in order. Not that there's anything wrong with the film's premise, which has been aided (for a change) in the dubbing process. Because the action is set in mid-Victorian England, it doesn't hurt to have the voices of Patrick Stewart and Alfred Molina as a father-son team of wacky Manchester scientists. Anna Paquin, pulling a Nancy Cartwright (Bart Simpson's voice), plays the tale's hero, a boy called Ray Steam.

A wild-eyed inventor like his aforementioned dad and granddad, Ray is happily tinkering along when a mysterious package arrives from grandfather. It contains a "steam ball", a small, black orb that packs enormous amounts of renewable energy.

Initially, the film's design, which resembles a 19th-century boy's adventure book come to life, conveys the wonders of the newly unfolding industrial revolution, with its myriad possibilities clouded only by thin wisps of dark smoke in the distance (just as the movie is draped with Steve Jablonsky's lugubrious or?chestral score.)

Soon, though, the adventure is sha?dowed by forces that view science merely as a tool to make war and money-preferably at the same time. Once young Ray catches up with his forebears, the movie devolves into a series of long-winded conversations about technological militarism, interrupted by increasingly convoluted battle sequences that do little but (ahem) celebrate the glories of same.

This wouldn't matter too much if Otomo, working from a script he wrote with Sadayuki Murai, had given us a rich cast of characters. But after introductions are made, everyone settles in to his or her role as a mouthpiece for rather obvious attitudes about science and its misuses. The most irritating person on the scene is probably young Scarlett O'Hara (I kid you not), the daughter of an unseen industrialist. She likes Ray but has only the most egotistical grasp of the issues at hand. Still, she has the wherewithal to stop one endless discussion by yelling, "I'm getting sick of your annoying philosophies!" Frankly, my dear, you're onto something.