When Charles Dickens died, he left his final novel unfinished. Dickens's "The Mystery of Edwin Drood" is a murder-melodrama that fails to solve its readers' most irking question -- who killed Edwin Drood?

As New Canaan High School's drama company polishes for its opening performance of the classic whodunit, the cast is learning how best to rehearse Rupert Holmes' musical rendition of Dickens' incomplete script. It's a stage play that has a definitive finale -- but they don't yet know what it will be.

In Holmes' take on Edwin Drood, the audience chooses the ending. The final half hour of the musical lies completely in the hands of its spectators.

"I just can't wait to see what happens," said senior Gelani Alladin. "The fact that the audience chooses a different murderer every night means that there are so many possibilities. There are hundreds and thousands of variations to the ending and we have to be prepared to play out them all."

In character, cast members will descend into the audience with scorecards to tally each audience member's vote on who finished Drood. Audience members can also cast their votes by applause on other outcomes left unraveled in Dickens's script.

"If we didn't have the audience, we couldn't do the show," said senior Katie Oxman.

There's no doubt about it -- the audience is integral to the production. But heaps of time and talent from the 104-member cast are also key components to the recipe that results in a show of such complexity.

"It really all starts about a year before the show even happens," Alladin explains. "We know what the show is going to be about a year in advance, so very early on I research the background of the show to figure out what part I'm interested in. ... I also research the time period and how people behaved during that time period. I read the script over and over again and eventually everyone has to write a biography of their character so that we have a solid idea of who these characters are."

When the parts are divvied up, rehearsals commence. The cast meets six days each week, Monday through Saturday. A typical week of rehearsal totals 26 hours, Alladin said.

Once rehearsals begin, the first task at hand is learning the music. But it's not just about hitting the right notes. The cast must also learn to move to those notes.

Keri DeTullio, 16, is co-dance captain. Myriad styles of dance are sprinkled throughout the show and DeTullio helps teach them to the cast. Spectators can expect to see routines with tambourines, waltzes and lots of leg-lifting cancan, she said.

Next in the pecking order is blocking, the act of mapping out each actor's position on the stage as the show moves from scene to scene.

As assistant stage manager, Becky Thompson, 16, is tasked with plotting on paper the location of every actor and prop throughout the show. If a cast member forgets his or her placement, Thompson is charged with directing them to their mark.

"Each big set piece has its own little parking spot backstage, too, so that everyone knows where it is when it needs to be brought on stage," she said.

Once a scene is blocked, the actors who appear in that scene must have those lines memorized, Alladin said.

"And while all that is going on, the technical work is being done," he explains. "During the summer, [the director] looks for props and the crew comes in after school and starts to put all the pieces together and build the set. As they finish with them, the actors get to use them."

There are designated crew members to assemble the set, but the actors pitch in, too. Alladin said he helped construct many of the major props including a fireplace, Christmas tree, bed, gravestones and plexiglass dinner table.

Once blocking is complete, the company begins to rehearse the show from start to finish.

"We try to clean up everything and put it all together," Alladin said. "Then we do a sing-through with the whole orchestra."

Alyssa Thompson, 15, is a violinist in the pit orchestra. She said practices with the orchestra every day after school in the month leading to opening night. A standard rehearsal lasts five hours and includes one 15"-minute break, she said.

"There's a lot of pressure to practice at home, too, because the music is very, very difficult," said Thompson, who also pitches in by sewing and altering costumes. "You can't miss a rehearsal or you're out. It's a lot of work, but most of all it's a lot of time. It takes so much time to put everything together."

When the singers have synchronized their voices with the band, the company begins to rehearse in costume.

"I think the hardest part is conserving our energy throughout the last two weeks and really going for that final stretch," Alladin said. "It's not like we're professionals and we get to sleep all day and then come to rehearsal. We have school and we have other important things in our lives that are tiring as well. So it's really important that I save up my energy, save up my voice and just keep myself healthy and moving forward, because when we start running through the show full-out with all of the components, we're really giving it our all. And then it just magically comes together."

Sophomore Michael DeMattia agrees that it takes a little bit of magic and a lot of hard work to put on a show as intricate as "Edwin Drood."

DeMattia, 15, is the production stage manager. He's second to the director, meaning that of all the cast and crew, he holds the most power.

"This isn't my first show, so my peers do, I think, take me seriously when I tell them what to do," he said. "They know not to mess with me, especially in these last two weeks before we open."

DeMattia is the liaison between each production component: the director; the cast; the crew; the orchestra and the designers. His primary task is to keep the company on task.

"It's a lot of phone calls, a lot of e-mails and a lot of day-to-day meetings to make sure that we're all on the same page because if we have a disconnect -- that's deadly," he said.

It's a 40-hour per week job that DeMattia says pays off in many ways -- just not in dollars and cents.

"I'm going into a completely different direction -- medical school," he said. "But I still think that what I do here prepares me really well. I work with so many different people and do so many different things on a daily basis that multi-tasking has become a nice, easy, daily routine skill for me, and that's really valuable."

Oxman, 18, plays the narrator and boss of the British theater company. Like many members of the cast, Oxman is happy to spend her afternoons, evenings and Saturdays in the high school auditorium.

"I'm so crazy [and] I love it so much that it's not hard for me to put this first because I want to make it happen," Oxman said last Saturday, 10 rehearsal days from opening night. "Like right now, I'm making a prop. It's not really my job, but I want to do it. I want to make it into something even more amazing than it is. The hard thing for me, I'd say, is to always have the energy to do other things like find the time to sleep and do schoolwork. But being here and even staying later than I need to isn't the hard part about all this. That's what's easy."

Oxman is in the process of auditioning for musical theater programs at several different colleges. She attributes her preparedness for university-level theater to the professionalism of the high school's drama company.

"This is a great background to prepare me for the real thing, because this pretty much is the real thing," she said.