 On the same day, Friday the 13th, Topaze calls on the Baron de La Tour-La Tour's mistress, Coco (Myrna Loy), who is looking for a tutor for her sister's son, Alphonse, and had gotten Topaze's name from La Tour.Upon meeting and listening to the sincere remarks of Topaze, the baron, head of the La Tour Chemical Works, decides to employ him as a scientific front for his phony curative water.After an encounter at a cafe, where the Baron narrowly avoids a scene with his wife by calling Coco "Madame Topaze", Coco reveals the true nature of her relation to the Baron to the naive Professor.