In the teen sci-fi thriller "Kin," a shy 14-year-old kid finds unearthly powers in the vacant warehouses of Detroit — an intriguing if standard young-adult premise that dissolves before your eyes in this inept and erratic directorial debut.

Jonathan and Josh Baker's "Kin" expands from their 2014 short "Bag Man," a film that must have shown enough promise to attract a topline cast featuring Zoe Kravitz, Dennis Quaid, James Franco and a couple prominent late cameos in the full-length feature. But "Kin," as is common to late-August releases, has the uneven, half-baked feel of franchise designs gone bust.

It stars newcomer Myles Truitt as the young Eli, whose adoptive family could be cheerier. Quaid plays his gruff blue-collar father; the mother is gone; and his older brother, Jimmy (Jack Reynor) is just getting out of prison after six years. A not great situation quickly goes downhill when Jimmy's brutal debtors (led by Franco's maniac gangster) come to collect.

When things get bloody, Jimmy misleads Eli about what's happened, and the two flee westward with a bag of cash, uprooting from the dark streets of Detroit for a cross-country chase that, to a surprising degree, plays out at a Midwestern strip club, where they meet Kravitz's stripper, and a Reno casino. Before leaving, Eli, while wandering the vacant buildings on his bike, comes across an alien gun that proves predictably handy in the showdowns to come, but that also sends a pair of very human-sized aliens on his path, speeding along — just like the extraterrestrial pursuers of "Under the Skin" — on motorcycles.

But should a movie about a parentless 14-year-old be centered on a gun, one that only he can fire? Is that empowering? The underlying odiousness of the gun violence — both regular and ray — in "Kin" is particularly questionable given its PG-13 rating.

But the bigger problems in "Kin" have more to do with the script by Daniel Casey which takes implausible turns without grounding any of the action in the characters. Given the film's title, and that the filmmakers are themselves twins, you would expect the brother relationship at the heart of the movie to be something more than it is. But Eli and Jimmy seem worlds apart, even when they're talking to each other. For a movie centered on brotherhood, it's remarkably empty of any sense of kinship.

When one character chases after them, she sums it up: "$60,000 and a space gun? Who the hell are you people?"

"Kin," a Lionsgate release, is rated PG-13 by the Motion Picture Association of America for gun violence and intense action, suggestive material, language, thematic elements and drinking. Running time: 102 minutes. One and a half stars out of four.

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