Behind closed doors, Mansions of Madness Vol. 1 contains five scenarios for use with the Call of Cthulhu Starter Set or the 7th Edition Call of Cthulhu: Keeper Rulebook. It includes two fully updated and revised classics, along with three brand new adventures, all suitable for up to six players and their Keeper.

Each scenario can last from one to three sessions and serves as a fitting next step for those who have already experienced the horrors of the Doors to Darkness and Gateways to Terror scenarios. Here are the five scenarios:

• Mr. Corbitt: Does a seemingly shy and retired local businessman hide a terrible secret? Can the investigators solve the puzzle and save the day?
• The Crack'd and Crook'd Manse: Long considered a cursed place by the people of Gamwell, it seems that Fitzgerald Manse has finally escaped its wretched past. However, no one has seen the new owner, Arthur Cornthwaite, for quite some time.
• The Code: Called to the home of Dr. Kenneth Connolly by an urgent telegram, can the investigators piece together the strange events plaguing Wellington Manor?
• The House of Memphis: The world-famous magician Memphis the Great has not been seen for weeks. Has he merely gone on another legendary journey, or is there a more sinister reason for his disappearance?
• The Nineteenth Hole: Renovation work at Thistledown Golf Club has not gone smoothly. Stories of illnesses, ghost sightings, and now no one can find the owner. Dark shadows loom over Scotland, and not everything is as it seems.