The duo help reorganise the seed museum owned by the descendants of famous botanist Edwin Pargeter - but it is not long before a man is found dead in the family's garden. In an effort to trace his killer, Rosemary involves colleagues from the Royal Horticultural Society at Kew Gardens, and soon the race is on to identify a batch of mysterious seeds before it falls into the wrong hands.

Laura and Rosemary are hired to re-create a Victorian garden in Regent's Park, where they meet all manner of intriguing characters - but the oasis of calm in central London is shattered by the discovery of a body. The victim is a respected Harley Street psychiatrist - whose three-legged dog appears to hold the key to solving the case.