The Mardi Gras Mystery

From the back cover: Trapped in the House of Blood! You're in New Orleans, spending the Mardi Gras holiday with your uncle. One night he takes you to a masked ball at the mysterious Maison du Sang, the House of Blood. You've just stepped inside the ballroom when a sinister-looking servant approaches your uncle. "The hostess wishes to see you alone," he says. Now you're left in the ballroom without him. What do you do?