PLAYING A PERILOUS PART. Miss Katherine Billings was cast in a most unlikely role for a vicar's daughter. But beautiful Kate was an impoverished orphan -- and her only escape from a lecherous employer's embraces was to go upon the stage. It was dangerous enough that a charming French playwright wanted her as his leading lady, and an ambitious impresario demanded that she bare her charms to an eager audience. But when a magnificent marquess, Lord Henry Grayson, proposed that she join him in a masquerade of mating in a mock marriage, Kate found that putting on an act in public could be even more perilous in private . . . if the act was an act of love . . .