How does the author use foreshadowing in Suspicion?

The author uses the technique of foreshadowing at the beginning of the story when Mr. Brookes comments on Ethel's stellar performance with the young Mr. Welbeck in a performance of a play entitled Romance last year. By the end of the story, it becomes clear that Ethel and Welbeck have been having an affair, which is the impetus for Ethel's attempts to poison her husband.