Synopsis of Bitter End
The story starts out where someone has evidently tampered with a jar of pate at the residence of one Nero Wolfe. Poison is suspected and an outraged Wolfe vows to find the dastardly culprit behind this assault on his palate.
As fate would have it, Miss Duncan, niece to My Tingley of Tingley’s Tidbits who makes the pate, arrives to engage Wolfe to investigate the product tampering.
Among the close knit circle of suspects is: Miss Yates, in charge of production; Mr Cliff, a VP of a competing firm; Philip, Mr Tingley’s adopted son; Mr Judd, a mysterious banker who is also looking to buy Tingley’s Tidbits; and Miss Murphy, assistant to Miss Yates.
The investigation takes a turn for the worse when Mr Tingley is found murdered in his office and Miss Duncan apparently struck unconscious at the scene.
Synopsis taken from https://en.wikipedia.org/wiki/Bitter_End_(novella)