"He'd give me a quarter. I'd go to the Coke machine and get a Coke. It wasn't until years later I realized what a genius my father was — he got someone to pick up all the cigarette butts and trash for a quarter, and then he got that quarter back. I thank my dad all the time; I went to business school all those years working at the motel. It was great," says McDonough, seated in a secluded hotel side-lobby.

He'd given up his dreams of acting when he received a phone call that was to change his life.

"I got a call from my manager saying, 'I've got this audition for you in this thing called 'Band of Brothers.' I had this small part. Went in there, and there were 50 people in the room and Tom Hanks. I had no idea he was going to be in the room. Sitting there was Tom Hanks, who is literally my hero ... I'm sweating bullets — it's TOM HANKS.

"And finally he talks to me, and within three seconds we're like buddies. He knows how to diffuse tension so easily. He's really quite fantastic at it. Finally, I said 'OK, who am I reading with?' figuring it would be one of the casting directors. He said, 'No, you're going to read with me.'

"That was probably my greatest acting lesson of all time, because here's a two-time Academy Award-winning actor, and if he's reading this small part with this relative unknown actor, he must be doing it with 500 other guys. The humility that Tom has," he says, shaking his head.

"Knowing he has all the talent doesn't mean you have to stop being a great human being. And Tom has ... I get choked up every time I think about it."

McDonough read that small part and was encouraged to try out the next day for the larger role of Buck Compton, one of the gutsy American soldiers in the miniseries, which Hanks was co-producing with Steven Spielberg. But it was three months before final auditions, and now it was down to 30 actors.

"Spielberg's running around with this little DVD camera getting in everyone's faces. And me, as a performer, I was loving it," he grins. "I guess I gave my best that day. I got a call the next day saying, 'OK, get ready to go to work.' And goodness gracious, it was a thrill."

McDonough was memorable as the heroic Compton, so indelible that he was cast as the mercurial district attorney in NBC's late, great "Boomtown."

And at 9 p.m tomorrow, he premieres as the aggressive doctor who heads up a team of canny sleuths in NBC's "Medical Investigation."

Here the culprit is not some human miscreant but mysterious maladies that suddenly strike sections of the population with no seeming cause or cure. The show settles into its regular 9 p.m. time slot on Friday.

McDonough is elated that he's back in front of the camera, but he says he learned early on to take things as they come.

"I happened to be the youngest of six kids, and all the other five happened to be phenomenal at everything — great athletes, great scholars, great speakers, great everything. So I tried to figure out what I wanted to do, and I really wasn't sure," he says.

"My freshman year in high school I was failing every class. Nothing was working for me. Then I auditioned for this play, 'You're a Good Man, Charlie Brown,' and I played Snoopy. And that first night on stage — it was really just working the character and doing something I'd never exposed myself to.

"I'd tried out for plays in the first, second, third, fourth, through the eighth grades, and they all said, 'No, no no.' Then I got 'You're a Good Man, Charlie Brown' and everyone was, 'Well, of course. Look at you. You're perfect for this kind of stuff.' From then on in I just loved it."

He was accepted at the prestigious London Academy of Music and Dramatic Arts. But McDonough quit after only six months.

"I left because I didn't like it. Here I was, 21 years old in London, this foreign place, and here's this kid from small town Cape Cod; I didn't understand any of it. I couldn't understand the subways. I couldn't understand what was going on. I got lost. I was still so immersed — I'd played baseball at Syracuse, too. I didn't know what to do, so I came back here and studied here," he says.

Back from Britain, he decided to try his luck in Los Angeles. He climbed into the back of his friend's Ford pickup and headed west. His first day there he landed a job, even before he found an apartment. But the job lasted only six hours.

"They fired me because I was terrible," he says, closing his eyes.

"I worked at all kinds of jobs, at UPS, worked at delivering Christmas trees, worked in carpentry, plumbing, selling pens over the phone, selling cars. You name it, I did it.

"I lived very frugally and had a very inexpensive apartment, a very inexpensive car. ... I never complained about it. I enjoyed it."

But McDonough couldn't get cast in anything. "My first few years out here it was kind of like the first grade, second grade, third grade — 'No, you're too Irish. You're too Nordic. You're too this or whatever.' I dyed my hair black for years and figured that would help. And that certainly didn't work. And finally things started to cook with 'Band of Brothers,' and I was the luckiest guy in the world."

It was back to England for "Band of Brothers," and it was on St. Patrick's Day that he met his wife, Ruve Robertson, a South African working in public relations in England.

It was love at first sight, he says, tears puddling his ice-blue eyes. "She was, 'Who is this Irish guy?' She didn't understand.