Saturday's opening (after previews from July 12) marks the end of a process started in 2004 when writers Paul Sportelli and Jay Turvey (who share book, music and lyric credit) began developing their musical through a series of readings and workshops at The Shaw and later at the Tarragon Theatre in Toronto.

This is the first new Canadian musical ever presented at the 45-year-old Shaw Festival, which focuses on plays by George Bernard Shaw and his contemporaries, or plays related to the period in which he lived.

Tristan performances play in rep to Oct. 6 at the intimate Court House Theatre. Sportelli is Shaw's music director, and Turvey is a Shaw ensemble member.

Eda Holmes directs the production. The musical is based upon Thomas Mann's tragic love story about "the age-old struggle between desire and duty." According to Shaw Festival notes, "Set in a spa high atop the German Alps at the turn of the century, patients, visitors and staff witness the flourishing relationship between the dark poet Spinell (Jeff Madden) and the luminous Gabrielle (Glynis Ranney), taken away from her husband and child to recover her ailing health."

It's billed as "a vivid adaptation of Thomas Mann's short story of a forbidden love affair." In the musical, "the conflict between duty and desire is clear, also at stake is the fundamental issue of freedom — of choice, of expression — as Gabrielle's forbidden but impassioned playing of Wagner's famous aria from Tristan and Isolde thrusts everyone into a new, unexpected drama."

Sportelli and Turvey "were inspired to adapt Tristan into a musical in part because Mann wrote so beautifully about music in the story."

The cast also includes Neil Barclay as The General, Donna Belleville as Frau Spatz and Patty Jamieson as Fraulein von Osterloh; as well as Krista Colosimo, Jane Johanson, Gabrielle Jones, Peter Millard, Graeme Somerville and Mark Uhre.

Musical direction and orchestrations are by Paul Sportelli, set design is by Judith Bowden, costume design is by William Schmuck, lighting design is by Kevin Lamotte and dramaturgy is by artistic director Jackie Maxwell.

For more information visit www.shawfest.com.