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Lt. Frank Cioffi of Boston Homicide — the cop in Curtains — has nothing on The Drowsy Chaperone's sit-by-the-phono nerd who's only alive when listening to arcane showtunes. Well, one thing maybe: a badge. He's Drowsy's Man in Chair — with Badge, and that badge has gained him backstage access to a world he has only dreamed about — the world of theatre.

It's 1959, and at Boston's Colonial Theatre a westernized, musicalized version of Robin Hood — called Robbin' Hood — has just touched down before a paying audience. As if the launching wasn't rocky enough, somebody got to the thoroughly loathed leading lady, Jessica Cranshaw (Patty Goble), and slaughtered her before the critics had a chance to.

Enter Lt. Cioffi, Columbo of the Rialto, determined to solve the case — and the show. He sequesters the celebs and puts them to work on rewrites, while he sifts through clues. Meanwhile, they're falling like flies in the flies, and the increasing clutter of cadavers messes up his muses.

When he first lines up the usual suspects — the brassy producer (Debra Monk), her philandering hubby (Ernie Sabella), the ingenue (Jill Paice), her understudy (Megan Sikora), the barely married songwriters (Karen Ziemba and Jason Danieley), the serpentine director (Edward Hibbert), the wily investor (Michael McCormick), the stage manager (Michael X. Martin) and the choreographer (Noah Racey) — Cioffi utters a line you never expected to hear from a hard-nosed gumshoe: "It's an honor to be onstage with each and every one of you." David Hyde Pierce has no trouble delivering this line because "it's absolutely true." He practically makes it sing, being a team-player from way back (with four Emmys and six American Comedy Awards to show for his 11 years as Niles Crane, the twitchy, snooty younger bro of "Frasier"). When that series ran its course in 2004, he scampered straight for Spamalot and played that Pythonian Punch-and-Judy show till Curtains came to call.

"That's three for three," by his math. "I think you get a real sense of how much fun we, the cast, have together. When you see people onstage loving what they're doing and loving who they're working with — that's the thing that's infectious for an audience. I've had the same experience over and over of working with people who were really close, really loved each other and had a good time together."

So what's the secret of his smooth sailing? "I have a feeling it's the people I'm drawn to working with and the material I'm drawn to working on. There's something maybe more of an ensemble-team feeling to it — but, whatever it is, I've been very lucky, very blessed."

Ensemble, one suspects, is the only way he knows how to do it. All four of his Broadway outings have been team efforts. He arrived very, very late into the second act of his first, Christopher Durang's 1982 Beyond Therapy: He was the never-seen waiter who, when a gun accidentally goes off, bolts through the swinging kitchen door like the proverbial shot, producing the biggest laugh of the play. When he took over Boyd Gaines's Tony-winning role of the gay pediatrician in The Heidi Chronicles, he was spotted by the "Frasier" people, who thought he looked enough like Kelsey Grammer to write him into the series as his brother. (Oliver Stone saw John Dean in him and cast him so in "Nixon.")

At 47, Pierce is undergoing a major-chord image change from what has solidified in the public mind after that decade-plus of weekly exposure. He is hanging a sharp right into musical comedy, and Spamalot and Curtains are steps one and two in that direction.

The show-buff sleuth of the latter is not at all dissimilar to the equally shy-guy knight of the former. Sir Robin favored showtunes and had his own, "You Won't Succeed On Broadway (If You Don't Have Any Jews)." Truth to tell, Pierce now candidly tells it: "I guess it's because secretly I've always wanted to do a musical on Broadway."

Between these two characters and The Drowsy Chaperone's Man in Chair, the audience is well represented. "Cioffi, as an outsider coming into the theatre, is a guy who has always loved the theatre, who has always wanted to be onstage and wanted to do one of these shows — and that's who the audience is. He is Man in Chair. The difference is that Drowsy is a deconstructed musical, whereas this is a through-written storyline in the traditional musical sense. The brilliance of The Drowsy Chaperone is that they were able to give you the essence of what is bright about a traditional musical in a very untraditional way because he's constantly interrupting it, explaining things. Curtains actually is a traditional-styled musical. There is a plot. It never steps out of itself."

Curtains, which has a book started by the late Peter Stone and finished by Rupert Holmes, is the 12th Broadway score by John Kander and the late Fred Ebb. Director Scott Ellis, who helmed some "Frasier" episodes, pitched the project to Pierce. "I never will forget the way Fred's eyes lit up when I mentioned David for this role," Ellis recalls. "There was nothing better than Fred Ebb getting excited about something. He was like a little kid. He said, 'Oh, my God! That's perfect. I love him.' The only thing I regret is Freddy's not around to see this magnificent actor take this role."

It's a role that will take Pierce out of the ensemble and maybe up to the Tony podium — a notion he is quick to poo-poo: "Well, I've had the privilege of seeing Raúl [Esparza] in Company, so I'm able to put away my thoughts about any Tony Award because I thought he was so amazing in that role." Read like a charter member of the ensemble — to the end.