Some things are better left concealed... The Trail of Cthulhu Keeper's Screen gives you the most important tables, rules and references for GUMSHOE. Combat, contests, tests and the mind-shattering Stability tables are there at your fingertips, giving you more time for GMing, and less fumbling through rule books. And, on the players' side, Jérôme Huguenin's breathtaking artwork will add to your game's eldritch atmosphere. With the screen is the Keeper's Resource Book; not the last scribbled words of a madman, but a carefully researched collection of clues, special benefits, game-relevant historical data, NPCs and occupational information for use in play. Each ability is listed with 1930s equipment and practices focussed on their use in adventures to bring your game to life. Sprinkle the sample clues we provide, and offer the listed special benefits to your players. Occupations have detailed backgrounds you can use to flesh out character backgrounds and NPC contacts; discover their techniques, weaknesses and foibles. Need a mad scientist or a fence? Select from a range of NPCs, some throw-away thugs and cultists, others, detailed contacts with forbidden knowledge, partrician academics, antique book dealers and professional rivals. Each NPC has three quirks or mannerisms so that you can roleplay them consistently, and hooks they can provide to your players. Finally, there is handy Sanity and Stability summary, with page references to the main book. With amazing artwork, and superb resources, forbidden knowledge has never been so much fun!