The TV series based on Bong Joon-ho’s 2013 dystopian sci-fi movie Snowpiercer (which itself was based on the 1982 French graphic novel Le Transperceneige) has been in the works for nearly five years, cycling through various creative teams and networks. The show was originally developed by Terminator: The Sarah Connor Chronicles creator Josh Friedman, with a pilot directed by Doctor Strange’s Scott Derrickson, but the version now premiering on TNT credits Derrickson only as an executive producer, while Friedman gets co-creator billing with Graeme Manson.

Manson, co-creator of Orphan Black, is apparently the person who finally came up with workable version of the show, and his solution is to turn Bong’s bizarre, haunting vision into a police procedural. Manson’s Snowpiercer is mediocre and a far cry from the ambitious weirdness of the movie. However, it' a watchable basic-cable sci-fi series. It takes the same core concept and expands on it, replacing inexplicable mystery with dull exposition. Some of that was probably necessary in order to sustain an ongoing series, but it misses the point of adapting such strange, singular source material.

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As in the movie and the comic, the Earth of the TV series has been frozen solid thanks to a failed attempt to solve global warming, and the only humans left alive are packed into Snowpiercer, a massive 1,001-car train that circumnavigates the world. The train is a microcosm of the class system, with wealthy passengers who paid huge sums of money for their places in the luxurious first class, followed by skilled professionals in second class, low-level workers in third class, and the stowaways (who forced themselves onto the train as it was first leaving) in the tail, where they are forced to live in squalid conditions and subsist on slimy protein bars.

That’s where Andre Layton (Daveed Diggs) has lived for the seven years that Snowpiercer has been in operation, and as the first episode opens, he’s preparing to lead a rebellion, much like Chris Evans’ character in Bong’s movie. There are a few touches in the early episodes that recall the movie, including a rebel from the tail section being punished by having their arm thrust through a porthole in the side of the train so that it freezes off.

But that scene also encapsulates the difference between the two versions: In the movie, the character being punished wears a cartoonishly large clock around his neck, like a sci-fi Flavor Flav, to time how long it will take for his arm to freeze. On the show, the bureaucrat doling out the punishment marks the time with a completely normal-sized stopwatch that she holds in her hand. It’s more practical, sure, but it’s also less imaginative.

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That applies to the show as a whole, in which Layton works to foment rebellion, but he also uses his pre-apocalypse skills as a homicide detective to solve a murder on the train. Before he can lead his fellow “tailies” in a revolution, Layton is plucked from the tail by order of Melanie Cavill (Jennifer Connelly), the train’s head of hospitality and the conduit for orders from the mysterious Mr. Wilford, who created and runs the train but is never seen. A dead body has been discovered stuffed into a compartment, and Melanie needs the murder solved so she can maintain order. Apparently Layton is the only person on the entire train with detective experience in his previous life.

So the show turns into a murder mystery, at least for the first half of the 10-episode season, while also exploring the society on board the train, which resembles pretty much every other dystopian sci-fi society. While Bong’s movie started at the tail and moved inexorably forward, the progression of the story mirroring the physical progression of the characters, the series shifts perspective back and forth right from the beginning, focusing on characters from all sections, including a well-to-do first-class family with connections to the murders, a third-class “brakeman” (Mickey Sumner) who serves as Layton’s partner, and Layton’s former co-conspirators, left behind in the tail.

Diggs makes for a bland protagonist, who spends half his time doing typical TV-cop things and the other half expressing vague discontent with the class system onboard the train. Connelly fares better as the woman who essentially runs all of human society but is still beholden to snotty rich people, and Melanie is the only character with any real complexity. The numerous supporting characters mostly just fill space in the overly cluttered plot, although the murder mystery lets one background player come to the forefront as a particular character’s sociopathy is slowly revealed. The Americans’ Alison Wright comes closest to matching Tilda Swinton’s grandiose performance as the movie’s villainous middle-manager, although that mostly just means that she wears a similar fur coat.

Bong’s movie was a stylized wonder of set design and cinematography, but the series (with a pilot directed by TV journeyman James Hawes, who replaced Derrickson) has a generic sci-fi look, and the action could just as easily take place on a spaceship or an underwater outpost (the underwhelming CGI effects would be the same in all cases). Manson makes a few ill-advised attempts to expand on the technology of the train, but trying to explain it just makes it seem less believable. At least Bong embraced the ridiculousness of the whole idea.

After the recent historic Oscar win for Bong’s Parasite (itself in development as a TV series for HBO), this would be the perfect time to bring the South Korean filmmaker’s style to American TV. Instead, TNT’s Snowpiercer imposes the style of bland American TV onto Bong’s movie, and it doesn’t serve either particularly well.

Starring Daveed Diggs, Jennifer Connelly, Alison Wright, Mickey Sumner, Susan Park, Iddo Goldberg, Katie McGuinness, Lena Hall, Annalise Basso, Sam Otto, Roberto Urbina, Sheila Vand and Jaylin Fletcher, Snowpiercer premieres May 17 on TNT at 9 p.m. ET/PT.

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