A crank letter in the form of a manifesto is received at the offices of Metropolis Pictures, Hollywood. Its authors make perfectly clear their disapproval of the man assigned to write the script of the forthcoming Sherlock Holmes adventure film. It is signed "The Baker Street Irregulars" - the actual name of a group of distinguished Sherlock Holmes aficionados.

This strange communique from the "BSI" is the first indication that Metropolis Pictures is in for an enormous amount of trouble. But they can't possibly yet guess that they are in for a murder! Readers who revel in a foolproof murder mystery, who want fast pace, action, and wit, as well as the vast public who still delight in the Holmes legend, will find this thrilling detective story and cheerful Sherlockian frolic a superb adventure in suspense.