Sir Bohun Chantrey, who was both wealthy and eccentric, numbered among his enthusiasms an absorbing admiration for Sherlock Holmes.  To celebrate that great man’s Anniversary, he gave a party at which the guests were invited to impersonate characters from the Holmes stories.  A good time would, no doubt, have been had by all, if only the struggle for Sir Bohun’s money had been less competitive, and if he himself had not suddenly and, to the dismay and consternation of his relatives, announced his decision to marry a governess.

Fortunately Mrs Bradley and her secretary Laura Menzies were among the guests, so that when events took a very wrong turning, she was on hand to investigate a rapidly deepening mystery.