Six months ago, aliens invaded America and turned ER's pensive Dr. John Carter into gunslinging history professor Tom Mason, star of the new sci-fi epic Falling Skies. Noah Wyle's transformation from network doctor to cable action hero comes complete with scruffy beard and a scratchy voice that occasionally recalls a young Clint Eastwood. It takes a couple of hours, or roughly the length of the premiere, to get used to this new version of Wyle, but he pulls 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. Wyle's Tom is second in command to Will Patton's flinty Desert Storm vet Captain 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, zombielike followers when a skin-piercing ''harness'' is attached to their spines. It's a good, creepy effect.
There are familiar rhythms to this genre that Falling Skies can't help falling into. For instance, an 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 chaotic world they're trying to regain control of. Because Tom taught the American Revolution, he draws comparisons between the 18th century and the Falling Skies world that are heavily echoed by some of the show's military leaders. 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 influence via executive producer Steven Spielberg.
So far, its most interesting character is the anarchic leader of a band of marauders, John Pope (Colin Cunningham), who's as twitchy and sarcastic as Tom and Weaver are earnest and sincere. Pope, and Cunningham's sardonic performance, provide Skies with some much-needed flashes of sharp humor. Ultimately, though, Falling Skies rises above any one performance; it's the spectacle of humans versus aliens that draws you in. B+