Enola Holmes, an exceptionally intelligent, independent and fearless detective, is once again involved in a new adventure. This time, the danger threatens Sherlock Holmes's loyal friend and assistant, Dr. John Watson. The doctor has disappeared without a trace. This story hits the front pages of the newspapers. The most disturbing thing is that nothing has been heard from the kidnapper (if he has really been kidnapped): he neither demands a ransom nor makes any promises.
While the police are puzzled, Enola decides to act herself. She goes to visit Dr. Watson's wife and it is there that she discovers a dangerous clue: strange bouquets that Mrs. Watson receives one after another. These bouquets are made of completely unsuitable plants, and Enola soon realizes that the kidnapper is not silent. He sends messages in the "language of flowers"... and these messages indicate death.
Time is running out. Can Enola Holmes solve the mystery and find Dr. Watson before it's too late?