In The Onyx Lobby by Carolyn Wells (1920)

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About the author: Carolyn Wells (1862-1942) was married to Hadwin Houghton, the heir of the Houghton-Mifflin publishing empire. Like Mary Roberts Rinehart, being in a publishing family created an easy pipeline for getting her works into print. She wrote a total of more than 170 books, including 61 Fleming Stone detective stories. See this Wikipedia article.

Carolyn Wells

Major characters:

Sir Herbert Binney, baker of 'Binney's Buns'
Miss Letitia Prall, "The Grenadier",
Richard "Rick" Bates, Letitia's nephew
Eliza Gurney*, Letitia's companion

Mrs. Adeline Everett, a widow
Dorcas Everett, Adeline's daughter, engaged to Richard Bates
Kate Holland, Adeline's maid

Julie Baxter, employee and drama queen

Crippen, of Crippen's Cakes, a rival baker
Vail, a rival baker

Gibbs, a detective
Corson, a detective
Bob Moore, elevator operator, fan of detective stories
Pennington "Penny" Wise, a consulting detective
Zizi, Pennington's assistant

Locale: New York City

Synopsis: Sir Herbert Binney, successful baker in England, has come to the US to expand his business. He wants to enlist his distant relative Richard Bates, by offering to make him heir to his empire if he accepts.

Bates lives with his aunt, Miss Letitia Prall, who has a long-running undefined feud with Adeline Everett, who lives in another apartment in the luxurious Campanile. Adeline's daughter, Dorcas Everett, is secretly engaged to Bates.

Eliza Gurney*, companion to Letitia, catches on and spills it to Letitia, which escalates the feud.

While Bates is considering whether to 1) accept Binney's offer and 2) continue his engagement, Binney is found dead in the Onyx Lobby. He had just returned from a dinner out with his chorus girl friends.

The murder weapon is a knife from Letitia's apartment.

*Her last name is inconsistent - usually Gurney, but sometimes Grundy.

Review: I was only a few pages in when I realized I have heard a similar plot before. Two single parent figures, neighbors, having a long-running but unexplained feud - and their children secretly in love? This is the same plot as the 1960 off-Broadway musical The Fantasticks; but its heritage goes back much further. Wikipedia states: "The musical is based loosely on The Romancers by Edmond Rostand, which draws elements from the story of Pyramus and Thisbe, Shakespeare's Romeo and Juliet and A Midsummer Night's Dream, and Donizetti's L'elisir d'amore."

It is hard to imagine all this jealousy around a bun recipe, but here it is. Sir Herbert Binney is a colorful character, enjoying his nights out with the ladies, but always 100% proper; putting them in a cab when the date is over, never accompanying them to their homes. He meets his end quite quickly.

The bulk of the book consists of arguments and name-calling between the two feuding ladies. They enjoy their unexplained feud so much that when one moves, the other follows; that it may continue. The sniping could be cut in half without affecting the plot one bit.

Penny Wise and Zizi arrive, and the discovery of the hidden recipe is an amusing episode. As usual, Penny doesn't do much except propose motives, with Zizi doing the legwork  - in the style of Nero Wolfe/Archie Goodwin.

When the killer is revealed we are hit in the head with a serious violation of the Rules of Fair Play (which, I concede, came later - in 1929). No spoiler, but beware of the plot element which claims the murderer is one with specific medical knowledge.