When Miss Violet Montgomery, daughter of late Hatton Garden Jeweller Harry Montgomery, writes to Sherlock Holmes asking for his help in solving a theft from her family home, the famous detective takes little persuading to agree to the case. Unbeknownst to Miss Violet, two years previously - and a few weeks before her father's death - Harry Montgomery had written a similar letter to Holmes, who was abroad at the time and unable to assist. Harry...