I love the future world that writer-director Jake Paltrow has painstakingly built in his sci-fi Western “Young Ones.” I’m less enamored of who he put in that world, and what he had them do.

The film is set in a near future where droughts have decimated an area that we’re to presume is somewhere in the American Southwest (but actually filmed in a remote part of South Africa). Water is scarce, and what little can be found is pipelined to big commercial farms.

That leaves small farmers like Ernest Holm (Michael Shannon) fighting for what drops he can get, and fighting literally. In the opening scene, he kills two water thieves trying to break into his well. The well is dry anyway – Holm earns his living ferrying alcohol and other supplies to the water miners up in the hills.

Ernest is fiercely convinced that the water will return, and he keeps his daughter Mary (Elle Fanning) and son Jerome (Kodi Smith-McPhee) working the land. But unsavory characters abound, including thieves, vagabonds willing to sell their baby for cash, and a wealthy neighboring family whose land has been irretrievably ruined by the use of pesticides. The son in that family, who has the mustache-twirlig name of Flem Lever (Nicholas Hoult), has been romancing Mary against Ernest’s wishes.

As the family patriarch, Shannon brings a humanity and gravitas to this new Wilder West setting. But each “chapter” of Paltrow’s screenplay focuses on a different character, and once Ernest’s chapter is over, “Young Ones” reveals itself to be pretty thin on both plot and characterization. Paltrow said he was inspired not by old Westerns or sci-fi movies, but S.E. Hinton young adult novels.

 But his teenage characters don’t have the passion or depth of “The Outsiders,” say. Hoult, a good guy in “Warm Bodies” and “X-Men: First Class,” seems to relish playing a darker character But Smith-McPhee is pretty flat — a subplot involving a girl he meets at a border crossing takes a good while to go nowhere. And the inevitable confrontation between Flem and Jerome takes so long to develop, there’s none of that feeling of mounting stakes you expect from a Western showdown.

That said, there are some neat ideas in the details, mixing cutting-edge technology with retro frontier touches, such as robot pack animals that resemble giant beetles, click-clacking across the sand. The film uses some CGI, but Paltrow said the robot was mostly a giant puppet operated by two parkour athletes, who must have been very, very hot.

But then, when the robot pack animal is the most compelling character in your movie,  you’re having problems.