The Midnight Feast is a classic example of a whodunit—a subgenre of mystery story in which the reader is progressively given clues to figure out who committed a crime, hence the name: whodunit or “who done it.” In the case of The Midnight Feast, the reader learns by page 31 that there is a dead body. Throughout the rest of the story, Lucy Foley presents the reader with different suspects, each of whom has a motive for the murder. Structurally, Foley employs a classic feature of a whodunit plot: the double narrative. One timeline of the narrative follows the events as they happen openly and chronologically. The second timeline includes the narrative of events from the past that inform the present-day investigation of the crime. A double narrative can be revealed through flashbacks, dialogue, or retellings, and, as in the case of The Midnight Feast, personal journal entries. The novella Murder on the Orient Express by Agatha Christie (1934) and the film Knives Out (2019) written and directed by Rian Johnson represent classic examples of whodunit narratives.

The whodunit mystery genre relies on several tropes and clichés, many of which are found in The Midnight Feast.