The case of the Overdue Library Book.
The investigators thrown together by fate :-
Raleigh St. Clair - Scarred by the battlefields of the Great War, this English academic is currently working as a high school teacher in Arkham.
Phil Lyons - The highly qualified assistant Medical Examiner for Arkham, immune to scenes of gore and slaughter and with excellent connections to the police and legal fraternity.
Tristan Tibbs - Itinerant street performer and magician eeking a living from Arkham's tough streets.
------------------------------------------------------------------------------------------------
A mutual acquaintance of the investigators sent them a request for help. A trail of grisly murders and mismatched library books led them around Arkham and to horrific discoveries in the catacombs beneath the staid office of the Nathan Thompson Institute.
------------------------------------------------------------------------------------------------
Outcome: The investigators were unsuccesful in clearing the name of their friend who is now on the run, however they were able (with the use of dynamite) to destroy the corrupt laboratory they discovered. Raleigh St. Clair now suffers from Nyctophobia. Raleigh St. Clair and Phil Lyons both acquired some mythos knowledge.