Can Lawrence Kingston unearth the key to a deadly secret hidden by a mysterious ancient garden inscription in the newest English Garden Mystery?

Codebreakers have tried for centuries to decipher the enigmatic inscription on a strange monument in the garden at Sturminster Hall, but no one has ever succeeded. When a murder occurs on the garden grounds, the intellectual puzzle becomes all too real, and Dr. Lawrence Kingston—retired professor of botany and reluctant sleuth—is called in to investigate.

Other than a scrap of paper bearing a random sequence of letters found on the victim, the police have no meaningful clues. Convinced that the crime must be linked to the seemingly unbreakable centuries-old code, Kingston begins hunting for clues that will help him unmask the murderer's identity as well as the arcane mystery of the monument. But he quickly finds himself swept along in the dangerous undertow of a centuries' old family conflict and a second murder, by poisoning. What could be so valuable, so important to justify such extreme measures and complex codes to keep sacrosanct for over two centuries?

To unlock the garden's dark secret, Kingston must delve into the brilliant minds of three famous men to fathom what part each may have played in masterminding the riddle: an Admiral hailed as father of Britain's navy, the author of England's most celebrated poem, and Great Britain's first Prime Minister. But as Kingston's investigation into an England's past leads him closer to a killer in the very dangerous present, his own prospects for survival start to look less and less assured.