The Ritual Chamber is a small secret chamber inside the Library, accessed by placing the False Book in a special bookshelf slot. The Ritual Chamber contains a variety of items including sacrificial daggers and various reading materials.
Some of these can be dangerous to read unless the player stands on the Pentagram tile on the floor. The room consists of a table in back containing a special Talisman, and a shelving unit to the right of the entrance containing 3 daggers, 2 manuscripts (Signs and Rituals and The Sacrificial Dagger) and 2 books (Reflexions on the power of the verb and De Vermis Mysteriis).
The Ritual Chamber was used by Jeremy Hartwood to study the dark arts and Cthulhu-based magics. One of the daggers there was involved in the creation of the Vagabond, which is located outside of the chamber and in the library. A different dagger to the one that created it can also be used to banish or dispel the creature. Another important item is the Talisman, which provides the key to defeating the great evil in Derceto.