Looking into the case, Strangeways becomes acquainted with Dr. Loudron's unlikeable family, including his cold and clinical elder son, Dr. James Loudron; his younger son Harold, an ineffectual spouse overshadowed by his restless wife Sharon; his adopted son Graham, whose face (we are told repeatedly) resembles that of a fruit bat; and his daughter Rebecca, a nervous woman engaged to a volatile painter named Walter Barn. The detective picks through the clues and psychodramas to ultimately uncover a murderer, but not before another person is killed and Strangeways finds himself expected to play the role of third victim.
Nigel Strangeways made his first appearance in 1935, in the book A Question of Proof. This university-set début mystery is straightforward Golden Age detective fiction. Twenty-six years later, The Worm of Death synthesizes that traditional and popular clues-and-suspects genre form with something much more au courant: a psychological study of deviant characters shaking up societal norms. It's a useful distinction, because a person's enjoyment of this book (especially contrasted with the purer puzzle titles that preceded it) will depend on how comfortably one is with Christie-like clueing and Freudian analysis sharing the same page.
Psychological scrutiny, particularly in regard to character motives, certainly became more popular in crime fiction beginning in the post-war years, when puzzle-only fiction started to feel for many a bit hollow without emotionally complex or relatably flawed individuals to provide the appearance of verisimilitude. In Blake's mystery and suspense novels, this manifested in a display of overt (and usually dangerous or unattractive) sexuality: some women, like Sharon in this book, became calculating nymphomaniacs, aggressively throwing themselves at Strangeways, with Clare watching in bemused fashion. In Blake's men, there is evidence of literal or figurative impotence (Harold), aggressive overcompensation (Walter Barn), or, in the murderer's case, some fundamentally Freudian Oedipal issues. The diagnosing can feel a bit heavy-handed in these later books, especially since Strangeways is a bit of a cold fish himself: his relationship with Clare Massenger as written isn't nearly as egalitarian or inviting as the one Blake created for Nigel and his wife Georgia.