The plot might have been lifted from an old-fashioned showbiz movie: Devoted small-town siblings sing and dance their way to Broadway stardom—in competing productions. For Hunter and Sutton Foster, however, the story is nonfiction. Sutton, 27, stars in Thoroughly Modern Millie, while her brother Hunter, 32, leads the cast of Urinetown. "It's got to be a first," says Millie's director Michael Mayer.

The Fosters' shows are vying for a fistful of Tony Awards, including best musical. In a further twist Sutton copped a nomination for best actress in a musical. To win on June 2, she must beat four other actresses—two from Hunter's play. "I'm rooting for my sister and for Urinetown," Hunter says. Then, remembering his co-stars, he adds, "If any of the three win, I'll be happy." When Sutton turns doe eyes on him, he amends again: "But I'll be most happy if my sister wins."

The sibs have been applauding each other since Hunter made his debut in community theater at 13 as Linus in You're a Good Man, Charlie Brown. "I was mesmerized," says Sutton, who at 10 starred in a local production of Annie. Their family moved often—Bob, 54, is a retired GM sales rep, and Helen, 53, a homemaker—but the kids found a sense of belonging on community stages in Georgia and Michigan. Today both have also found love with fellow stage actors: Hunter met wife Jennifer Cody in Cats in 1993; Sutton's live-in boyfriend, Christian Borle, was a castmate in The Three Musketeers in '01.

Their near twinship extends so far, says Jennifer Laura Thompson, an actress in Urinetown, that "they even look alike. If you put Hunter in a dress, he's Sutton." They also think alike. "I'm glad we did this together," says Hunter. Replies Sutton: "Me too."