Thursday night will be a little like walking the plank for Marc Robin and Curt Dale Clark.

After 11 years in development, the couple's swashbuckling baby, "Treasure Island: A Musical Adventure," is making its world premiere at the Fulton.

This could be it. This could be — dare anyone think it? — the next "Spring Awakening."

Or it could be the next "Carrie — The Musical," that ill-fated, five-night flop that barely sucked in its first Broadway breath before exhaling its last.

"That's the thing about this business. You can all have the best-laid plans and all the money in the world behind a show and it won't go anywhere," Robin said. "Then some other odd little thing you never planned on becoming big will win the Tony Award."

"Treasure Island" is a little bit of both. What started out more than a decade ago as a one-hour kids' show in Chicago briefly ballooned into a musical monster in Peoria.

Now, at its Fulton premiere, after years of countless workshops and rewrites, it promises to be Clark and Robin's best effort. And there's more than a little at stake for the Lancaster couple who have collaborated in life and art for nearly 20 years.

Robin composed the "Treasure Island" score and directs its premiere run. Robin also wrote the lyrics and book with Clark, who also plays "Dr. Livesey" in the show. They've tirelessly courted industry movers and shakers to trek to Lancaster for the premiere in hopes it will wow them. They're even hosting a full slate of out-of-towners at their Lancaster home during the show's run. And if nothing else, they've sunk more than a little money into their dream of creating a show with enough legs to take it to other stages, if not all the way to Broadway.

Chasing the dream has conjured a palpable fear that they may jinx themselves merely by wanting it too much. And Clark's poker face is an especially easy read.

"It's a huge risk … and no risk at all," he said. "We've caught ourselves over and over again talking about (the show's) future. Then Marc says, 'Wait a minute. We worked and worked toward March 6. We need to have fun with this. If nobody else likes it and it's never (produced) again, we'll be proud of it and enjoy it while we have it.' So we're trying not to put any expectations on it. … With that said, we desperately want it to be (produced) again."

At that Chicago kids' theater, it was just a little something they threw together based on Robert Louis Stevenson's 1883 pirate adventure novel. It was supposed to run for nine weeks. It swelled into a nine-month run.

"It was unbelievable. It started winning new-works awards, reviewers started reviewing it," Robin said. "People were saying, 'Hey, you guys have got something here. Run with it.' It just seemed otherworldly how it took off."

A couple of years later, a Peoria theater had an open slot in its season. Clark offered their 10-actor show. Suddenly, tiny "Treasure Island" was hardly big enough for its unwieldy 42-person cast and all its new subplots.

Intrigued by the subject, Fulton artistic director Michael Mitchell flew out to see the Peoria show staged by the couple he'd long worked with in Lancaster.

"Michael thought it was a good play," Robin said. "But he said, 'You just need to get back to the roots of this thing and tell this kids' story. If you do, I'll produce it for you at the Fulton.' "

A couple years later, when "Pirates of the Caribbean" fever hit, Mitchell encouraged Clark and Robin to get back to work on the show.

Since then, they have reshaped 75 percent of the Peoria version. Over the past year, Fulton staff developed the show's moody, Tim Burton-esque design. In December, Robin cast the show, snagging Tony nominee John Herrera (best known for his role as Che in Broadway's "Evita") to play Long John Silver, and Chicago favorite Dale Benson, who reportedly gets applause in that town just for stepping on stage.

They generated early buzz in a notoriously fickle industry, thanks in part to elaborate treasure-chest-themed press kits bearing chocolate coins, eye patches and pirate pop guns.

The pricey ploy worked. The show not only got press previews in Playbill and other industry outlets, RSVPs rolled in to crank up the chances the right people will wash ashore on "Treasure Island."

"There are 107 artistic directors, producers and people who have the power to produce this play coming from theaters from all over the country," Clark said. "That doesn't sound like a lot, but that probably represents 20 percent of the industry."

Meanwhile, as Robin and Clark edge closer to the end of that plank, they're enjoying the walk.

"It's nerve-wracking, but I can't help it, I'm just so damn happy with it," Clark said, a little embarrassed to admit he likes his own show. "We have an insane amount of work to do, but I just can't wait for Thursday night. I'm so excited."

"Treasure Island," Thu. through March 22, Fulton Opera House, 12 N. Prince St., $20-$45, 397-7425.

E-mail: slindt@lnpnews.com