As hot as conditions are outside, the one holdout, Juror No. 8, ensures it will be hotter under the collars of these 12 men assembled to determine the guilt or innocence of a man accused of killing his father.
"I pretty much know if I had been on the jury on this case, I would have been one of the 11 that said guilty," says McDonald, the show's director. "Anytime I see something that challenges the way I would think, I enjoy it."
This production of the play by Reginald Rose certainly provides ample opportunity for introspection. As perceptions of truth and justice are peeled back, they reveal festering personal wounds that may or may not be informing deliberations.
In the spare jury room - Vienna brown walls with dark brown trim; a water cooler, flag and coat rack situated in various corners; a coffee pot set on a table against the back wall - tensions are mounting as the dozen jurors begin to hash out their differences.
Best known for its film incarnations - Henry Fonda and Jack Lemmon have each portrayed the soul-searching Juror No. 8 - the drama's pedigree does not cast as long a shadow on this production as one might think.
Charles Boyce, the Frederick, Md.-based actor portraying Juror No. 8, has purposely stayed away from the films to prevent those performances from informing his own.
After previous roles as John Hancock in McDonald's "1776" and Oberon in "A Midsummer Night's Dream," he says it feels good to inhabit a character he can add shading to without fear of reprisal.
"It's the way I think I'd be. Even if I didn't say my piece, it's what I'd be thinking," Boyce says. "With Oberon, you already know who he is and you know who John Hancock is. This is more of an everyman. I can put more of a characterization into it."
With McDonald taking notes from a first row seat, Boyce is under siege from 11 agitated men who all want to go home after six days of being stuck listening to testimony.
Convinced the defendant is guilty, their voices rise in agitation at the prospect of indulging Boyce's sole holdout vote.
Leading the charge is Juror No. 3. In his first acting role, Paul E. Bronner Jr. remembers less about the characterizations from the movies and more the tenor of the jury room: a claustrophobic cell with tempers flaring.
"He is an angry man, a lonely man," Bronner says of his character. "He hates the world, but deep inside he's angry with himself so he lashes out at the whole world and has created a shell around himself."
The battle of wills creates a palpable tension wrought tighter with each passing moment.
"There are a lot of strong personalities, which is good for the play because it's supposed to be that kind of play," Boyce says. "It's not hard to get the tension up. It's hard to maintain the tension."
Luckily, the confines of the stage help maintain a prickly, taught mood. But those same claustrophobic conditions create a challenge for McDonald.
To make the cerebral, dialogue-heavy show hum, she's been manipulating actors around the set's jury table centerpiece. Actors are always getting up to stretch, take off coats, grab a cup of coffee or stare out of the room's single window.
Reviewing evidence leads to role-playing exercises that work twofold by advancing the plot and providing an opportunity to engage the audience in more physical action scenes.
Still, the director doesn't lament the play's 12-people-stuck-in-a-room premise.
"It's a plus," McDonald says. "It's helped make the men understand it's all about the acting. There are no costumes to save them, no fancy sets to save them."
Bronner likens his approach to acting to a previous singing career.
"It's not what you sing, it's how you sing it. And with acting it's not what you say, it's how you say it," he says. "I thought the most challenging thing would be remembering lines, but that's not it. It's satisfying myself."
McDonald has always enjoyed depictions of the judicial process; her favorite scene in the Christmas season classic "Miracle on 34th Street," for instance, takes place in a courtroom.
Provided her cast members acquit themselves well, and she has a feeling they will, she's betting audiences will be as enthralled as she is.
"The systematic disassembling of the whole process and how (Juror No. 8) convinces this jury is just a fascinating process to me," McDonald says. "The fact that it's done so skillfully is so fascinating to me."