Content Warning: This section of the guide includes discussion of racism.

The navy plans to blow up the German U-boat today, and Lady Mercer reports that Rachel is on the way with her new fiancé, Percival Allerton, an American diplomat. She blames Constance for Mrs. Fog’s renewed friendship with the de Champneys and insists that there can be no whiff of “impropriety” until Rachel is “safely” married. Mrs. Fog reveals to Constance that the de Champneys’ parents were unmarried and that their mother was Black. This is why Mrs. Fog was forced to part from them in her youth and then again on the eve of her daughter’s wedding. Now, Mrs. Fog intends to marry Simon. Suddenly, a massive boom from the cannon shatters the window. Constance throws herself between it and the women, sustaining a small cut. Harris takes her to his mother’s suite, where he cleans and sews it up.

The de Champneys arrive to visit Mrs. Fog and meet Lady Mercer, and Mathilde identifies their “mixed blood” as the cause of Lady Mercer’s concern. She is worried about how this relationship might impact Rachel’s upcoming marriage. Suddenly, Rachel arrives, and the de Champneys leave quietly, insisting that Constance go to Rachel.