"I did actually think, 'This is the saddest thing.' Here's a leading actor in a Broadway show on his night off and he's sitting at home on his own. Nobody to see, nothing to do, nowhere to go. What am I going to do?"
Then his eyes fell on a copy of "Hamlet."
So Stewart cracked open a bottle of good Napa wine and settled down to reread another Shakespeare tragedy.
"It just turned into the greatest evening," says Stewart, wistfully. "After 50 years, it still takes my breath away."
During a conversation over soup and salad before a recent performance, one thing becomes abundantly clear: Stewart is a hard-core Shakespeare freak.
He's a man who memorized Shakespeare for fun as a teen and spent 14 years with the Royal Shakespeare Company. He never abandoned The Bard despite commanding a star ship for seven years on TV's "Star Trek: The Next Generation."
Even on vacation he can't let go: Stewart, who managed to slip away to the Caribbean for a few days before "Macbeth" debuted on Broadway, found that the misty moors followed.
"I was walking along the beach muttering the lines," he says, laughing.
There's little tropical heat in Stewart's "Macbeth," an updated, hair-raising interpretation that reeks of Stalin and Orwell. The single set and Soviet-style uniforms are augmented by a supernatural freight elevator, video projections and a kitchen sink - for Lady Macbeth to wash the gore. The Three Witches even rap.
Stewart, 67, who has grown a vaguely unsettling mustache for the part, portrays a Scottish king more Hamlet than Richard III - introspective, analytical, thoughtful, questioning. It's his first Macbeth.
"Nearly 50 years I've waited," says Stewart. "I learned it when I was 14. I memorized all the soliloquies just because I thought they were great. And they stuck, so I didn't have to learn those bits of the play, which is a blessing, because learning lines has now become the one curse of this job."
The production, under the direction of Rupert Goold, debuted in May 2007 at England's Chichester Festival Theatre, switched to London's West End and then moved to the Brooklyn Academy of Music before transferring to Broadway.
Stewart's performance has earned him some of the best reviews of his career. The Times of London said his Macbeth "is an enthralling creation of frailty, appetite, egotism and grim humor." The Daily Telegraph said he had turned in "a truly great performance."
His Lady Macbeth agrees. Kate Fleetwood, who is married to Goold, has found Stewart to be an actor of incredible energy and a playful leader of the company.
"I think he's invigorated by his successes over the past couple of years," she says. "The sweetness of what he's achieving now is all the more sweet because he's put the work in over the years."
Raised in Yorkshire, England, Stewart joined an amateur drama group at 12 and later won a scholarship to the Bristol Old Vic Theatre School, launching a career as a character actor.
"What I'm doing now is all I ever wanted to do. I didn't have any other ambitions," he says. "Once I'd been accepted into the Royal Shakespeare Company in 1966, I was perfectly content."
He stayed for an eyebrow-raising 14 years, playing everything from Mark Anthony to Henry IV to Shylock to Oberon. "People who were not in the company would say to me, 'Give it a break. Why don't you go somewhere else?' And I would say, 'To do what?"' he says. "Telly?"
Stewart eventually left to look for more modern fare. He had just done a production of "Who's Afraid of Virginia Woolf?" in 1987 when an interesting offer came along. "I found myself in Hollywood shooting a syndicated science fiction series, which I was assured would fail."
It didn't, of course. Thanks to Stewart's rich baritone and noble bearing, the "Star Trek" franchise ran for seven years, 178 episodes and produced four feature films.
Despite the Borg and Klingons, Stewart still managed to make room for blank verse. He established the Paramount Shakespeare Company, a workshop on Saturday and Sunday mornings for any actor interested.
"I was keeping my hand in," he says.
Part of his sci-fi life has followed him to Broadway. In his dressing room sits a boxed up Capt. Jean-Luc Picard action figure and a bumper sticker that reads "Picard/Riker 2008: Make It So."
The show gave him a higher visibility, which led to more work, including roles in the films "Conspiracy Theory," "L.A. Story" and the "X-Men" series, and Broadway, where he starred in "The Tempest," "The Caretaker" and multiple outings of his one-man "A Christmas Carol."
The lure of Shakespeare continued unabated, even if playing Hamlet, Romeo or Orlando were now out of reach. Lear or Falstaff or Macbeth were still manageable - and he leapt at the Scot.
Before the play arrived in the United States, Stewart spent a few days alone in Italy. He found himself in Florence, staring at Michelangelo's famous four unfinished slave sculptures, forever emerging from their blocks of stone.
"It was wonderful standing in front of them, because it became a very vivid symbol for me of what I actually feel creating a role. It's there and you have to strip away bits of yourself until - whoop - there's Macbeth."
Stewart already has more Shakespeare on the horizon. He's signed up to appear as Claudius for a six-month Royal Shakespeare Company run of "Hamlet." His yearlong journey in "Macbeth" is due to end on May 24 but, for Stewart, it will remain unfinished.
"You're never done - that's the great thing. I know come the 24th of May, we're going to be feeling like Liam Neeson's character in 'Schindler's List': 'I could have done more,"' he says.
"You can never say this job is done, mission accomplished. That's impossible with Shakespeare."
