'Mortal Engines': Worth the sum of all its moving parts

What is the true measure of a film adaptation of a book? Is it one that stays as faithful as it can to the book (like the first two Harry Potter movies), or one that tweaks the story but stays true to the spirit of the book (like the last few Harry Potter movies)?

Whatever the measure, it's hard to deny that one of the best books to movie adaptation ever has to be Peter Jackson's Lord Of The Rings trilogy, which not only stayed true to J.R.R. Tolkien's books but also added elements of its own to make it richer (though The Hobbit trilogy subsequently proved that too much of a good thing can be bad).

Above all, LOTR also built a world where we all wanted to see more and more of, which I personally feel has to be one of the most important elements in adapting science fiction and fantasy books, which are usually set in worlds that exist only in the author's imagination.

With that in mind, it's perhaps not surprising that I liked Mortal Engines so much (and not just because it was co-produced and co-written by Jackson).

An adaptation of Philip Reeve's sci-fi steampunk book of the same name, Mortal Engines is set in a post-apocalyptic world in which the entire world has been decimated by war. Cities have literally uprooted themselves and they rove the landscape on giant wheels in search of fuel and resources.

The largest of these mobile cities are known as "Predator Cities", which can literally swallow and "ingest" smaller cities, crunching them up for fuel and scrap metal.

Tom (Robert Sheehan) is a Londoner who has never been outside his travelling hometown, which is also one of the great Predator Cities.

But his life changes when he foils an assassination attempt by a mysterious girl named Hester (Hera Hilmar) on Thaddeus Valentine (Hugo Weaving), one of London's most powerful people, and whom she accuses of murdering her mother.  One thing leads to another, and the two are thrown out of London and have to rely on one another to survive in the Outlands, and somehow find their way back to London.

Cast wise, it's hard to fault the performances of the two leads: Hilmar and Sheehan do their best in a movie where they are literally overshadowed by the giant machines they are on. Weaving is his usual imposing self as the main villain, and he does more to build up the threat and menace of London on his own than all the heroes combined.

While the film alters quite a bit from the book's plot, it stays largely faithful to the story as wel

l as the major plot points of Reeve's novel.

The actual story may seem like a little formulaic at first, but the film is that much richer thanks to the world Reeves conceived, which director Christian Rivers does reasonably well to bring to life. The author built a world across four books that has so many moving parts (pun intended) that it would take more than just one movie to cover it all.

Indeed, perhaps the biggest frustration is that Mortal Engines only scratches the surface of this fascinating world. We only get to see London in all its glory, and not the other Predator Cities, and as well as some spectacular but rather shallow scenes featuring the airborne city of Airhaven and an ocean-faring prison.

The glimpses we get of these really made me wish Rivers had gotten deeper into the inner workings of these locations. Think Hobbiton or Minas Tirith in LOTR, where we got a true sense of what made those places tick and how its communities lived, rather than just a cursory "look how cool it looks!" sweep of its buildings and denizens.

Still, Rivers does build a world that is both believable and mysterious, and crams enough into the film to satisfy fans. He also manages to give a sense of scale that implies there is a lot more to this world we have not seen.

Besides, when a movie makes you want to go out and read the book again just to immerse yourself in the world more, you know it has done its job. Maybe that, more than anything else, is the true measure of a film adaptation of a book. The movie is directed by Christian Rivers, and  starring Hugo Weaving, Hera Hilmar, Robert Sheehan, Jihae, Ronan Raftery, Leila George, Patrick Malahide, Stephen Lang.

The writer is a film critic