Melissa Errico sweetly and brightly voices Clara, his mistress.

WSJ: Review: Intense revival of Sondheim's 'Passion'

First seen on Broadway in 1994, "Passion" is a Proust-flavored, operatically intense musical whose central character, an unattractive and terminally ill woman named Fosca (Ms. Kuhn), develops an uncontrollable obsession with Giorgio (Ryan Silverman), a handsome young soldier who is in turn involved with Clara (Melissa Errico), a young married woman.

WSJ: Theater Review: The Subtle Joys of Small-Scale Sondheim