How Does Your Garden Grow?

Hercule Poirot receives a letter for assistance from an elderly woman, Amelia Barrowby, who dies five days later. Poirot goes to the house and admires the well-maintained garden, with its spring flowers and edging of shells. He meets a young Russian woman, Katrina Reiger, who speaks cryptically of the money that by rights is hers. She is interrupted by the dead woman's niece, Mrs Delafontaine, and her husband.

Poirot interviews the local police inspector who tells him that they now know that Miss Barrowby died from a dose of strychnine but the problem is that the victim and her two family members all ate the same meal.

The next day brings the news that most of the estate has been left to Katrina, thereby providing a motive, and she is detained by the police.

Poirot calls at Rosebank and sees Mrs Delafontaine. At the front door, he points to the unfinished row of shells and points out they are oyster shells. The Delafontaines fed Miss Barrowby poisoned oysters and planted the shells in the garden to hide from Katrina and the maid. Mrs Delafontaine confesses that she and her husband had been pilfering money from her aunt for many years and could not let the estate go to Katrina.