There is a case of a failed suicide. This is brought to Sherlock Holmes' attention the next morning by a concerned granddaughter. The man was once a client of Holmes' years eariler in which the theft of a faboulous blue diamond was never solved. Many suspects are tossed before the sleuth- the haugty butler, mysterious gardener, two cloaked shadows following the detectives, the hot-headed grandson, or someone else lurking in the background? Soon, more bodies are found and all have connections to the family and a mysterious 'thief', known as 'Thames Weasel'. Will Sherlock Holmes and Dr. John Watson be in time to prevent another attempt, will Lestrade and his usual bumbling ways cloud the outcome?