The 'soiled doves' of San Francisco are being brutally slain, in a manner that reminds every one of the infamous Ripper murders in London the previous decade. When a mysterious English doctor in a steam powered horseless carriage shows up at the Garrison hotel, and then one of the murders strikes a little too close to home, twelve year old Wally Garrison and his cousin Gail begin an investigation of their own.Finding the killer will take them down some dangerous paths, and bring them into contact with some interesting potential allies and enemies. From the previously mentioned English doctor to the Scotland Yard Inspector visiting San Francisco on vacation to the butcher known as Leather Apron, the cousins need to figure out who they can trust, if they are to catch the killer in time!