NEW YORK (AP) -- These days, Noah Wyle occupies a world devastated by alien invaders.
On his new TNT sci-fi series "Falling Skies," he plays Tom Mason, a Boston University history professor whose wife was killed and one of his three sons taken captive in the alien attack.
Tom is second-in-command of a ragtag regiment of survivors in a ravaged Boston suburb. The odds against them seem insurmountable. But they are fighting back. In his new role, Wyle is facing even more challenges than, years ago, in that Chicago emergency room.
On "Falling Skies" (which premieres Sunday at 9 p.m. EDT) there are threats aplenty from the mysterious, multi-legged aliens (nicknamed "skitters" by the humans) and the killing-machine robots they sic on the Earthlings.
"But there are larger themes," Wyle says. "Beyond surviving, the human characters will need to create the template for the next civilization, which probably won't even be realized in their own lifetimes."
In short, Tom Mason is a history professor helping create new history by looking to the past.
"History is full of inferior forces creating so much trouble that the invading army leaves," Tom tries to reassure his comrades as he reels off several encouraging examples, including a modern case: "Red Socks, Yankees, `04."
Wyle says he wasn't looking to do another series and, while he isn't the first TV star to have said that, he makes it sound convincing. After all, his 11-year weekly hitch as Dr. John Carter on NBC's "ER," which ended in 2005, established him as a mainstay of the last blockbuster drama viewers may ever see. What follow-up series could measure up?
"After `ER,' I wanted to be a stay-at-home dad for a while," Wyle says. (Divorced last year, he has a son, Owen, now 8, and a 5-year-old daughter, Auden.) "The game plan, such as it was, was to stay away from episodic television, and try to rebuild my career in a post-'ER' world."
But the persistence of TNT (for which Wyle made three films in the "Librarian" adventure franchise) wore him down with offers for pilot deals, he says. So a couple of years ago, he sought out the advice of a trusted counselor. He presented his son, Owen, with three series options: He could be a lawyer or a police detective or an alien fighter.
Owen shot him a you're-kidding-me look, Wyle recalls. The choice was obvious: An alien fighter Wyle would be.
The impact of his decision? "To get this kind of street credibility with my son — it's huge," Wyle says with a smile.
"But with the birth of my kids, I started to really look at my career through their eyes more than my own," he declares. "So that does dictate choice, steering me toward certain things and away from other things."
Wyle had his own reasons, too, for saying yes to "Falling Skies." He identified with Tom's devotion to his sons, and admired Tom's sense of social duty.
"And there's the grief and loss that he struggles to rebound from," Wyle adds. "These are all themes I'm interested in exploring in my own life."
Now 40, he is 6 feet and 2 inches and rangy, and retains the boyish air that first earned him heartthrob status two decades ago. He is laid-back but reflective, with those arched, guileless eyebrows that seem to certify everything he says.
Wyle's co-stars include Moon Bloodgood as a comely pediatrician who lost her only son in the attack six months earlier. Will Patton is the hard-line commander of the regiment with whom Wyle's character often clashes. And Drew Roy plays Tom's oldest son, who fights against the invaders alongside his father.
Playing Tom's 8-year-old youngest son is Maxim Knight, who "paid me the nicest compliment he could have," Wyle says. "He told his mother after we filmed a scene that ended with us embracing, `He hugs like a dad.'"
Executive producers include Steven Spielberg, Graham Yost ("Justified") and Robert Rodat, who got an Oscar nomination for his screenplay for "Saving Private Ryan" and wrote the "Falling Skies" pilot from an idea he and Spielberg co-conceived.
The series was shot last July through November in Toronto and, says Wyle, "it was physically more demanding than most of the work I've done: a lot of running and jumping and diving and rolling. I got a lot of nicks and bruises along the way."
With post-production CGI churning out hoards of virtual foes, Wyle was also faced with "fighting tennis balls at the end of a stick." But other times, he did have a material version of a skitter to confront.
"We had a guy in a suit," he says, "which presented its own difficulties: The suit was very rich in detail but apparently hadn't been constructed to allow oxygen flow." This required frequent breaks in filming for the wearer to cool off.
For Wyle, a highlight of the shoot was when Owen came to visit. There, after observing a fight scene between Dad and an alien, he volunteered some pointers.
"I asked what he thought," says Wyle, "and he goes, `You're pulling the gun up too high. I can't see it in the frame. Hold it at shoulder level, as opposed to over your head, and it'll stay in the frame.'"
Thinking back on it, Wyle laughs the laugh of a proud father.
"I followed his direction," Wyle says, "and got his seal of approval."
EDITOR'S NOTE — Frazier Moore is a national television columnist for The Associated Press. He can be reached at fmoore(at)ap.org and at http://www.twitter.com/tvfrazier