Donnie Wahlberg Donnie Wahlberg

Taking a break between scenes, Blue Bloods' Donnie Wahlberg places two smartphones within easy reach. The onetime teen heartthrob is so connected to social media that instead of watching his hit cop show on Fridays at 10, he reads real-time Tweets to gauge what viewers like or don't. Happily for the actor who plays Det. Danny Reagan, the "likes" win — Blue Bloods and Wahlberg rule the night.

His fans are a large, loyal bunch. Long devoted to him from his boy-band days in New Kids on the Block (now reunited as NKOTB), they inundate the show's Brooklyn set with inspirational books, photo collages and vintage action figures. Many have even followed their hero to his CBS series. "Every day we're on a stage, [his fans] know where we're shooting," says Tom Selleck, who plays patriarch Frank Reagan. "They hang out all day. Donnie will go over and talk with them — he's good that way."

Fifteen years after he made the transition from music to acting, notwithstanding roles in such prestigious movies as The Sixth Sense and TV projects like Band of Brothers and Boomtown, the 42-year-old has the part he seems born to play. Chalk it up to good fortune. The show was casting in Toronto and Wahlberg just happened to be in Canada en route to a concert in Alaska when he got wind of the opportunity.

"We were having trouble finding an actor to play Danny," recalls exec producer Leonard Goldberg. "I looked at Donnie's reel and said, 'That's Danny Reagan!' He had the energy and the physicality. If Tom Selleck's police commissioner is the foundation of Blue Bloods, Donnie is the engine that drives the show. He brings such passion — and a little danger — to the police stories that it allows us to pause and do the family scenes that are the heart of our show. Without Donnie, it could become a little boring."

Wahlberg also nails the intimate interactions with both Jackie (Jennifer Esposito) — Danny's partner on the force — and wife Linda (Amy Carlson). Notes Goldberg, "We hear from viewers that their relationship is so real, and for the first time they're seeing what it's actually like to be married to a cop." Danny and Linda's marriage is one of the most solid TV relationships since Friday Night Lights' Taylors, a portrayal that Carlson wanted to emulate from Day 1. "Love is the basis of the relationship," says the actress. "Linda and Danny may drive each other crazy, but they are crazy about each other!" 

Tonight's episode movingly combines the procedural with the show's family values when an undercover detective, who's a friend of the Reagan family, is killed in a drug bust — after Danny and Jackie arrive a minute too late. "Danny knows it easily could have been him," says Goldberg. "And he has to call Linda because she's the godmother of the dead cop's new baby, who's soon to be christened. It hits him on both sides."

The episode ties into what's become a common theme on Blue Bloods: "Everybody is confronted with the life that he or she has chosen," says Wahlberg. "Whether it's the bad guy, his drug-dealing mom or the cops whose lives are in danger." A divorced father of two, Wahlberg says he can relate: "I'm in New York and my kids live in L.A.; I'm lucky if I can catch a little Skype time with them, because this is the life I chose."

Humor is the weapon Wahlberg chooses to cope with the long hours and freeze-your-butt-off New York weather. "He works more hours than anyone on the show, and he's doing jokes at 2am with the same energy that he had when he started at 2 in the afternoon," says Goldberg.

That geniality doesn't surprise Wahlberg's uncle Archie, visiting the set one February day. "Donnie was the comedian in the family," he reveals. "He was great fun as a boy, a great kid, and he's now a nice man." 

Wahlberg cops to being a cutup, dancing around the set and trying to make everyone laugh, even if the director has called for quiet. "Jennifer and I do everything in our power to keep the crew having a good time," he says. Despite his goofiness, no one should doubt his acting chops, Carlson cautions. "He's a prankster and he can get my goat, but I always have to be on my toes because he's so smart and so passionate."

The showbiz veteran also never forgets how far he's come as the eighth of nine poor kids (actor/producer Mark Wahlberg is his baby brother) from a tough Boston neighborhood. "I'd get punched if I'd talk about wanting to be an actor," he says. "I'm enough of a self-critic to keep it honest. There was a time when I was frustrated because I thought, my band is better than I'm given credit for and I can act as well. I have finally proven it, but it took 20 years. I probably wouldn't have been ready if everything was perfect years ago. Now when I'm out chasing bad guys, I pinch myself and say, 'This is outrageous! This is too good to be true.'"

Wahlberg's next step: directing an episode. "I have some homework to do first. I don't take the responsibility of directing Tom Selleck lightly. Tom is a formidable man. I want him to say, 'Hey, when are you going to do the next one?' as opposed to, 'Let's not try that experiment again,'" he says, imitating Selleck's sonorous voice. We'll bet on the kid from Boston.

Blue Bloods airs Fridays at 10/9c on CBS.

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