The German core book of John Sinclair.
Translated from the back of the book:
When reading the books, did you ever feel the urge to stand up and shout: "Don't go that way, John, don't?" Now you can prove that you've the guts to be a ghosthunter on your own!
This adventure game contains everything you need to follow the footsteps of John Sinclair and his team and fight the demonic forces spreading all over the world. Also included in this book is the kickoff for long-spanning campaign, taking place parallel to the Black Death meta plot of the novel series.