A random shot from a random gun brings multiple worlds into collision in “Babel,” an ambitious and somewhat exhausting new take on synchronicity.

This film forms a kind of trilogy on the subject, actually. Mexican director Alejandro Gonzalez Inarritu and screenwriter Guillermo Arriaga previously made two terrific films based on the notion of interlocking stories told non-chronologically: “Amores Perros” and “21 Grams.” It’s not too far-fetched to suggest that their efforts inspired last year’s Oscar-winner, “Crash.”

The gunshot happens in Morocco, in a little-populated area. Two shepherd boys, playing with their father’s rifle (a new acquisition for chasing away jackals), take aim at a tour bus rolling through the desert. They pull the trigger, because there is no way they could possibly hit anything.

The bullet enters the neck of an American tourist (Cate Blanchett), whose husband (Brad Pitt) frantically tries to find her help over the next few hours. This static situation is threaded through the rest of the movie.

We are also jumping around in time and space: to an illegal-immigrant maid (Adriana Barraza) tending a pair of U.S. kids, and taking them to Mexico with her for a family wedding. And also to a deaf Japanese teenager (Rinko Kikuchi), who desperately tries to find connection in the urban jungle of Tokyo.

For most of the 21/2-hour movie, we can only guess at how these different stories join up. That was also true of the other Inarritu-Arriaga pictures, but somehow here the stakes feel less urgent, and the subject less original.

Even the title – a reference to the biblical story of languages and incomprehension – is all too literal. And it isn’t language that trips up these lost souls, but their own faulty decisions.

Cate Blanchett does all right with a role that requires her to be semi-comatose for much of the movie. Brad Pitt, on the other hand, isn’t actor enough to lend any nuance to the feverish American abroad. Gael Garcia Bernal (who starred in “Amores Perros”) does what he can with an underwritten role, and the young non-actors who play the Moroccan boys are excellent.

It feels churlish to complain about such a serious, thoughtful film, and “Babel” does have a number of gripping sequences. But it tends to touch on big things – fear of terrorism, illegal immigration, resentment of America – without exploring them. The overall result is a disappointment, however admirable its goals.

Cate Blanchett and Brad Pitt star in “Babel.”