The theater is dark. Audience members silence their phones and unravel their last hard candy wrappers for the imminent performance. Imagine yourself backstage — that hushed corridor, the smell of dust and wood spicing the air. The lead actor prepares to step forth, voice ready to boom from the diaphragm. It is a part you have rehearsed for months. It is a part you may never play in front of an audience.

You are an understudy.

For those of us not fluent in the theater arts, an understudy is an actor who studies a part so that he may replace the usual actor (aka an “”upperstudy””) under circumstances like illness, loss of voice or serious injury.

Take Karl Hussey and Mike Reasor, two juniors working on their Bachelor of Fine Arts in acting. Both have performed many times in front of the curtain. You may have seen Hussey in “”As You Like It”” or “”The Shape of Things”” earlier this semester at the Arizona Repertory Theatre.

Yet both young actors find themselves backstage for the Arizona Theatre Company’s production of “”The Mystery of Irma Vep.”” Written in 1984 by playwright Charles Ludlam, “”Irma Vep”” is a penny dreadful come to life — a farce mixing Victorian sensibility with Hitchcockian suspense. Lady Enid is the silly new wife to Lord Edgar and can’t seem to make sense of the stodgy maid, Jane,or the ridiculous servant, Nicodemus, not to mention the host of local vampires and werewolves. Hussey recommends the show “”if you’re in dire need of a laugh and don’t mind a few corny jokes.

What’s remarkable about “”The Mystery of Irma Vep,”” is the cast size. Two men play six parts, with about 40 costume changes.

Hussey currently understudies for Bob Sorenson, who plays Jane Twisden, as well as Lord Edgar and an intruder. Reasor is the backup for Oliver Wadsworth, making up the second half of the cast as Nicodemus, Lady Enid and Alcazar. Arizona Theatre Company noticed both actors during what is known a “”cattle call”” — a unified audition for all students in the acting major. Arizona Theatre Company in particular is well known for hiring UA students as understudies.

For both actors, spring break 2011 ended on a high note when they were offered understudy roles in “”Irma Vep.”” Reasor had seen the play as a child and was excited to take part, remembering how funny the work had been. Hussey had never heard of the play. A few minutes with good-ol’ Wikipedia was enough to excite him for the experience.

In the past few weeks, things switched into high gear for Hussey and Reasor. Lines were memorized, costumes fitted and the process of learning not only the role, but how their upperstudies interpret the role, began.

Being a capable understudy requires a different sort of preparation than a conventional role. Instead of spending time onstage during the hours of rehearsal squeezed between classes, Hussey and Reasor could be found taking notes about blocking, directions and carefully capturing the nuances of their upperstudy’s performance.

“”In terms of the depth of research put into characters, I put in more for a full roll,”” Hussey said. “”Most of the research and choices are made from Bob (Sorenson). My job is to recreate it and mimic it. It’s like taking an outline and coloring in the lines with my own truth and discoveries.””

Reasor agreed about the importance of mimicking the lead actor while also infusing a bit of personality to make the role seem natural. “”There’s a huge amount of flexibility taken away as understudies compared to a role onstage,”” Reasor said. “”You come in as an upperstudy during the rehearsal process with choices made. As an understudy, I come in ready to watch, ready to observe and mimic to the best of my ability.””

Though they might never stand in front of a sold-out house, there is no lack of respect when it comes to being an understudy.

“”All actors have understudied at some time,”” stated Reasor simply. “”It’s a job without recognition, but it’s so needed.””

The big question is, why would someone ever go to so much effort and spend so much time for such a slight chance of being onstage? It seems like a lot of work for little payoff.

“”It’s about the experience and learning to become a stronger actor,”” said Hussey earnestly.

Both Hussey and Reasor raved about the opportunity to watch lead actors Sorenson and Wadsworth, as well as being under the direction of artistic director David Ira Goldstein and every individual they come in contact with in the theater environment.

“”There’s a lot of great experience from watching the upperstudies, to see the process and how flexible they are,”” Reasor said.

Ultimately, it’s an intimate experience in which two students learn to work seamlessly together. “”The Mystery of Irma Vep”” is the first time Hussey and Reasor have worked together beyond the classroom.

“”You have to have confidence in your partner,”” Reasor said. “”Everyone knows the show, so we can always bail each other out.””

“”The Mystery of Irma Vep”” opened on April 9 at the Temple of Music and Art and runs through April 30. In the meantime, we’ll try to not admit that we’re hoping for the lead actors to catch a 24-hour flu so we see just how talented an understudy can be.