"Suspicion" opens with Mr. Mummery, who, on his way to work, increasingly feels a stomachache. He tries to ignore it and continues to browse the paper, reading about, among other items, a cook who poisoned a nearby family. At the office, he works with his partner, Mr. Brookes. At one point, Mr. Brookes asks if Mr. Mummery's wife knows of a good cook. Mr. Mummery says no, in fact, they have just found a new cook themselves. The conversation turns to the arsenic poisoning case, for the still-at-large woman, Mrs. Andrews, may be seeking a situation as a cook.

By the end of the day, Mr. Mummery feels better. When he gets home, Mrs. Sutton, the new cook, tells him that his wife Ethel is not feeling well herself. Mr. Mummery visits her in the bedroom and decides that he will send her supper up. If...