The Mistral is the crack train which runs from Paris to the Riviera--and here it carries diplomat's daughter Nancy Lorrimer (an actress who has ""a marvelous creamy complexion"") and Eric Matthews, wonder-boy play director of New York and London (whose broad shoulders fill the doorway of her compartment). There's a bit of nastiness between them because of compartment-sharing. And then, on the Riviera, where Nancy's staying with a wealthy school friend, it turns out that the nearest neighbor is none other than actress Lily Lincoln, who seems to be having it on with. . . guess who? So there's a second obligatory angry meeting of Nancy and Eric. But proximity makes the hearts grow fonder, of course. And at last there's a night of love, but Nancy, hearing no proposal, refuses to be a mere mistress. She returns to the States and theater in Saratoga, New York. But guess who shows up on closing night with an offer to understudy Lily in his new play about Tristan and Isolde!? Yes, indeed. So--as Lily has a snit and walks out of her part--understudy Nancy travels to stardom while Eric uncorks a proposal. Complete with such lines as ""Come with me, Nancy Lorrimer, discard your inhibitions, your foolish pride"": mindless romance-that seems oddly out-of-place between hard covers.