Millicent Holmes arrives, on board the HMS Durning, in London, from New York, to join the rest of her family in attending the double funerals of her father, Sherlock Holmes and her best friend’s father, Dr. John Watson. Together with her friend, Miss Watson, Scotland Yard, and her American husband, they track down the killers of their parents except for one who has escaped.

Millicent Holmes starts her adventure where her father, Sherlock Holmes, left off with his last case.