You might say that the premise of Babel is: A film about people who do reasonable things with horrible consequences. The plot could be summarized as: A man sets off a tragic sequence of events, but they save his daughter. The moral: Don't casually cross cultures - people will get hurt.
The events are: A Japanese man on a hunting trip to Morocco gives his Moroccan guide his rifle as a thank-you gift. The guide sells the rifle to a neighbor, who has a problem with jackals eating his goats. The man gives the gun to his two sons, who are his shepherds. The young boys believe that the bullets are ineffective and accidentally shoot a tour bus. Eventually the boys are caught by the police and one of them is killed. Their shot at the tour bus hits a woman in the neck. The woman and her husband are on a trip trying to recover from the death of their baby, their third child. They are delayed getting home to San Diego because of the wife's injury. Their Mexican nanny is stuck looking after the kids on the day her son is getting married, so she takes them with her to Mexico. Her nephew, who drives her, gets drunk at the wedding and so has trouble at the border on the way back. He runs through the border and in an attempt to elude the police he temporarily drops the nanny and her two charges in the desert. They almost die but are rescued and the nanny is deported back to Mexico. Meanwhile, back in Japan, the hunter's daughter - who is deaf, is struggling with teenagehood, and whose mother has recently committed suicide - is coming close to killing herself. The serial number of the rifle has been traced to her father, and a policeman comes to question him about it. He is not home but the policeman has an encounter with the daughter, which finally breaks through her problems. The policeman leaves; the man comes home, and he is finally able to connect with his daughter.
For a movie with such an interesting premise and plot, Babel was badly made. Individual scenes are too long - most of the way through, the experience of the film is boring and unpleasant. There is no character development. We never really understand or come to care about any of the characters - their personal details are only presented insofar as they make their actions reasonable. The nanny's son and his bride are more fully developed than any of the central characters. The prevailing emotion in all the main characters is anxiety.
The film is ungenerous. There is no natural beauty, no architectural interest, just bleakness. Morocco (in reality a fabulous place) never looked so bad - all we see of it is rocky desert and mud huts. That anyone would choose to travel there is presented as tragic bad judgement.
And yet the film is really interesting. I'd say it's better thinking about after the fact than it is sitting through. I'd like to see it remade with a different director and different cast. Perhaps the couple could be British (then the choice of Morocco would be less odd) and some more interesting small cultural clashes could be added.