Say what you like about Alejandro Iñárritu and Guillermo Arriaga, but they know when they’re on to a good thing. Their last overlong, miserabilist compilation of loosely connected tales garnered plenty of acclaim, and why fix something that isn’t broken? In all fairness, 21 Grams was a good and in places a great film; and Babel, though by no means as successful, isn’t a bad movie. But what was novel and interesting only a few years ago – the interwoven story technique exemplified by Paul Thomas Anderson’s Magnolia – is increasingly becoming both tired and (in Babel‘s case, anyway), tiring.

This time around, we have four main plot lines set principally in four countries. In Morocco two boys accidentally shoot an American tourist, leading to a massive police hunt for imaginary terrorists, while the victim and her husband languish in a tiny village waiting for the US government to stop politicking long enough to rescue them. Meanwhile their Mexican nanny has to choose between looking after the couple’s two children or going to her son’s wedding across the border, and finally decides to take them with her, with predictably disastrous consequences. And finally, in Japan, a deaf-mute girl, tired of being isolated from the world, sets out on a quest to loose her virginity by any and all means necessary.

These three threads are clearly meant to relate, and presumably to tie together into some grander themes – of the failure of language and the inefficacy of free will in the face of human nature and causality. But if you were being cynical, you might argue that Arriaga just had three short scripts hanging around, none of them substantial enough to justify a full length feature, and decided to cobble them together into one vaguely coherent whole.

Which is all well and good, except that only one of the four – the Japan segment – is really good, whereas the two Moroccan stories are quite average and in no way justify their length, and the Mexican tale is both predictable and preposterous. Iñárritu is clearly a talented director, but he also has a tendency to overindulge, and there just isn’t any good way around the problem of cutting between four disparate and barely-connected plot strands. Iñárritu’s solution, of staying with each just long enough for it to become interesting and then dragging the audience away at the first suitable cliffhanger, is both frustrating and lazy.

But in most other senses, his direction is as impressive here as in his last two films – engagingly stylish, but not in a way that overwhelms his material or cast. What problems there are with Babel really come down to Arriaga’s script. For a start, the guy just can’t write dialogue: There are whole scenes that are nothing but exposition, there’s barely any character building, and what there is is perfunctory and heavy-handed. But it’s nothing compared with when he tries to make a point – then the sledgehammer really comes out. His authority figures (usually policemen of one nationality or another) are quite bewilderingly stupid, and for the most part remarkably and needlessly thuggish. And yet thanks to the script, his characters are so obscure and unmotivated that it’s often hard to sympathize – this is why the Mexican tale, in particular, falls so flat. Watching bad things happening because people behave stupidly is thoroughly depressing, but it isn’t tragedy.

At this point, it’s probably worth repeating that Babel isn’t a bad film, only a frequently messy and flawed one. It’s worth noting the soundtrack, which is remarkably good, to the point where it plasters over some of the more painfully slow moments. The Japanese segment is mostly superb, and genuinely touching in the way that the rest of the movie is presumably supposed to be. And the others are just about held together by excellent acting – Adriana Barraza as the nanny in the Mexican tale has the hardest job and the least to work with, but her utter helplessness as she watches her life explode is genuinely moving. If only everybody had a script to work with that wasn’t so utterly two-dimensional then Babel would be probably be brilliant. But they don’t. And it isn’t.