Of all the musicals out there, “The Mystery of Edwin Drood” might be the one with the largest number of clever conceits, thanks to writer Rupert Holmes.

Holmes took the unfinished novel of the same name by Charles Dickens, who died before he could complete writing it, and imagined a way to stage it.

He did that by presenting it as a show within a show — a group of 1895 London stage actors are performing “The Mystery of Edwin Drood.” So the real actors are playing fictional actors, who are playing fictional characters. Got that?

Holmes also has them break the fourth wall, talking and joking with theatergoers.

And here’s the kicker: That ending Dickens couldn’t provide? Holmes decided to let the audience handle it. At each performance, theatergoers vote on who the killer is, as well as who a mysterious detective really is and which characters become a happy couple.

The result is somehow both high-brow and low-brow, with a Dickensian wealth of characters and intricate plotting, and but also with lots of broad comedy.

Goodspeed Musicals is producing “The Mystery of Edwin Drood,” which premiered on Broadway in 1985, for the first time, and it’s given a lively production under the always-top-notch direction of Rob Ruggiero.

“Edwin Drood” references the England Music Hall tradition, as well as the Brit genre of the panto. American audiences are not as familiar with those, so I’m guessing there is a lot that English audiences appreciate in “Drood” but American ones don’t get. (Fans of Norwich Arts Center’s annual panto, though, know the concept.)

One of the panto elements is to have a woman taking on a male role, and so Mamie Parris portrays Edwin Drood at Goodspeed. Or, more accurately, she portrays actress Alice Nutting playing Edwin Drood. As Edwin, Parris walks with a bantam strut and bristles with brash confidence. As Alice, she’s a petulant star, always stroking her blonde ponytail as if it were a cat.

In “The Mystery of Edwin Drood,” Drood is engaged to young Rosa Bud, but his uncle John Jasper — who happens to be Rosa’s singing instructor — is secretly obsessed with her.

Riley Noland is all wide-eyed purity as ingenue Rosa, and her voice is likewise pure and pretty, particularly on the ballad “Moonfall.” (The music in general tends to reflect the time frame of “Drood,” and it’s all beautiful and admirable, though not the kind of thing you’ll be humming on the way home.)

Lenny Wolpe brings a kind and gentle presence to the role of the narrator, who guides us through the multi-strand plot and abundant characters. When another actor, according to the script, doesn’t show up, he also takes on the part of a mayor, and does a bang-up job of talking with a faux-flawed Scottish burr.

Wolpe and Paul Adam Schaefer, bringing a haunted quality as well as a sense of simmering danger to the character of Jasper, duet on one of the most amusing (and astounding) songs of the night, “Both Sides of the Coin,” in which they spit out supersonically fast patter in unison. It’s quite a feat of teamwork.

A striking sequence in an entirely different way is what I’ll call the opium ballet. When Jasper is indulging at an opium den, he imagines himself and Rosa dancing. The dreaminess of the sequence, which gives way to nightmarishness for Jasper, is evocatively conveyed by James Gray’s choreography.

As the proprietor of that opium den, Liz McCartney has great fun playing Princess Puffer, the kind of character who, in a thick Cockney accent, proclaims “Bloody hell!” She encourages the audience to sing along with the chorus of her song “Wages of Sin,” and they enthusiastically do.

You are part of the show

Now about that audience participation: It starts before the curtain goes up. Actors, in costume and fully into their characters, stride through the auditorium aisles, engaging the crowd.

When they get onstage, Wolpe tells everyone where their participation will come in during the show (that includes hissing and booing for the villain), and he leads theatergoers in a comically elongated chant of the name “Edwin Drooooooooooooood.”

Later on comes the time for spectators to weigh in on how “Drood” ends. Actors again head into the audience, where they count hands raised for each character.

Seeing the actors waiting to find out what the conclusion will be and then act it out is quite entertaining, adding an element of surprise. The result seems primarily scripted but with welcome improvisation, too. It makes you want to go to another performance just to see how that day’s culminating plotlines shake out differently.

A feast for the eyes

The clothing, with costume design by Hunter Kaczorowsk, is tasteful and elegant, as befits with era, with parasols and bustles and morning suits.

The set, with scenic design by Ann Beyersdorfer, is as meta as the show itself: the Goodspeed Opera House’s embellished theater balcony looks as though it wraps around onto the stage. There are two spiral staircases, and sitting on the “balcony” onstage is the band.

It reflects the nesting-doll and you-are-part-of-the-show concepts of the “Drood” storyline — and it’s also, on a more basic level, just very cool.

If you go

What: “The Mystery of Edwin Drood”

Where: Goodspeed Opera House, 6 Main St., East Haddam

When: Through June 2; 2 and 7:30 p.m. Wed., 7:30 p.m. Thurs., 8 p.m. Fri., 3 and 8 p.m. Sat., and 2 p.m. Sun. Also, 2 p.m. on select Thursdays and 6:30 p.m. on select Sundays.

Tickets: Start at $30

Contact: (860) 873-8668, goodspeed.org