Published and set in 1940, this isn't a Nero Wolfe novel, but it's set in the same universe: Rusterman's is the best restaurant in New York. What this *is*, is a Tecumseh Fox mystery, Stout's lesser-known creation.
Amy Duncan, who once worked for her uncle Arthur Tingley of Tingley's Tidbits, is now a PI: one of Dol Bonner's 'siren squad'. Unfortunately, Ms. Bonner's current client is that selfsame Tingley. Tingley makes the best appetizers money can buy, and somebody's started sabotaging them by adulterating them with quinine. Could it be engineered by the Products & Beverages Corporation, or Consolidated Cereals, who both want to buy out Tingley's? Is it just a crank? Or is it something more personal?
Amy suspects Dol may be double-crossing Tingley, when she sees Dol at Rusterman's with a P&B vice president, so when she meets Fox by chance, she asks for advice. (She's on such bad terms with her uncle that her attempt to talk with *him* ended by her storming out.) Within a day or so, though, Tingley telephones and asks Amy to call on him, and she finds him in his office, throat cut, just before being knocked cold.
While the initial calling in of the police is a bit muffed, somebody for once shows sense: Fox sees to it that Amy is 1) put under a doctor's care, and 2) provided with a sharp lawyer before the cops get to her.
We have, among others: 1) Philip Tingley, Arthur's adopted son and heir, but the business is tied up in a trust controlled by some senior employees, fanatically devoted to the company. (He's a grapefruit with delusions of grandeur, and his crackpot economic theories take up too much time.) 2) Leonard Cliff, the VP seen with Dol Bonner, who seems to have a romantic interest in Amy. Dol Bonner, despite her connection with Amy, appears only twice, in passing.
All in all, a decent story, but Fox doesn't narrate, and lacks the character development of the inhabitants of Wolfe's brownstone, so it seems a bit thin compared to Stout's other work. If you'd like to see this same story recast as a Wolfe story, check out "Bitter End" in _Death Times Three_, Stout's last published collection.