The "Cthulhu Casebook" contains nine independent adventures set in the 1920s, plus numerous articles and aids generating many other plots.Certain portions of this book are easily included in ongoing tales -- "The Mauretania" can expand any ocean voyage; "The Asylum" can make exciting an otherwise uneventful institutionalization; "The Auction" can be used to introduce various artifacts to aid or hinder the investigators.

Other sections contain full independent adventures playable by themselves or useful in filling gaps between campaigns or as subplots within current story lines.