By Ken Tucker
June 20, 2011 at 06:20 AM EDT

Six months ago, according to TNT’s new sci-fi would-be epic Falling Skies, aliens invaded America and turned ER’s pensive Dr. John Carter into a gun-slinging history professor, Tom Mason, star of the show. Noah Wylie’s transformation from network doctor to cable action-hero comes complete with scruffy beard and a scratchy voice that occasionally recalls the young Clint Eastwood. It takes a couple of hours, or roughly the length of the premiere, to get used to this new version of Wylie, but he pulled it off.

A similar, gradually developed, but decisive conviction makes Falling Skies an engaging, if derivative, chunk of dystopian sci-fi. The series benefits from its structure. Rather than wasting time showing us citizens’ surprise and horror at the alien invasion, Skies begins in the thick of the organized resistance to it. Wylie’s Tom is second in command to Will Patton’s flinty Desert Storm-vet Weaver, and the two have frequent clashes in strategy. Add Moon Bloodgood (Terminator Salvation) as an appealing pediatrician and there’s a budding romance with widower Tom in the midst of this grimy battle.

The humans’ foes are Mechs (big, bipedal metallic-looking creatures) and Skitters (lower-to-the-ground spidery creatures). They’re not invulnerable – as Tom says, “They die just like us, you just have to get close” when you shoot them. The invaders take human prisoners for slave labor, including one of Tom’s sons, Ben (Connor Jessup), who are turned into obedient, zombie-like followers when a skin-piercing “harness” is attached to their spines. It’s a good, creepy effect, that also serves as a good, creepy metaphor for parents of adolescents. Teens (they do comprise most of the work-force we see in the pilot) compelled to behave and do as they’re told. Nightmare or dream, depending on who’s doing the imagining…

The metaphor of invading forces enslaving and mass-killing humans the invaders consider their inferiors operates on a more overt level as well when, in the next episode, Tom will explicitly compare them to Nazis. I’m not sure how far Falling Skies wants to go down that road, although based on the four hours I’ve watched, the military strategy sessions would not be out of place in a WWII film as directed by Howard Hawks, with lots of eye-level shots of men taking the measure of each other under the stress of battle.

There are familiar rhythms to this genre that Falling Skies can’t help falling into. For instance, any given action scene – Tom and his team attacked by Mechs and/or Skitters – is invariably followed by one in which characters pause to reflect upon or argue about the anarchic world they’re trying to regain control of. Because Tom Mason taught the American Revolution, he draws comparisons between the 18th century and the Falling Skies world that are also echoed by some of the show’s military leaders, and which can be heavy-handed. Many of the scenes between Tom and his sons (his wife was killed in an early invasion attack) are nicely quiet yet deeply heartfelt, a welcome Spielberg influence.

So far, its most interesting character is the anarchic leader of a band of marauders, John Pope (Collin Cunningham), who was taken prisoner by Tom and Weaver, and who will prove his value as a cook. Pope, and Cunningham’s sardonic performance, provide Falling Skies with some much-needed flashes of sharp humor — every war story needs an unpredictable man with few scruples to throw everyone else’s morals (or lack of them) into high relief. Ultimately, though, Falling Skies rises above any one performance; it’s the spectacle of humans versus aliens that draws you in. Call it old-fashioned, but sometimes, old-fashioned works.

Twitter: @kentucker