After spending decades living in the shadow of his more famous and successful sibling, Consulting Detective Sigerson Holmes is called upon to help solve a crucial case that leads him on a hilarious trail of false identities, stolen documents, secret codes... and exposed backsides.
The corpse of a shabbily dressed young woman has been discovered in the mud flats of the Thames at low tide. Police assume she's a prostitute, but Dr. Watson suspects something more and goes to his old friend Holmes, now retired and at very loose ends.
During WWII several murders occur at a convalescent home where Dr. Watson has volunteered his services. He summons Holmes for help and the master detective proceeds to solve the crime from a long list of suspects including the owners of the home, the staff and the patients recovering there.