The Book of Dagon
Only a single complete copy of this hand-written book is known to exist. Translated from R'lyeh glyphs by the hand of Obed Marsh, it consists of a saga-like history of the deep ones and their relationship to Cthulhu. Bed learned how to translate the glyphs from Walakea, chief of the Kanak tribe that worshiped the deep ones. It is unknown if he left notes regarding their translation.
The manuscript came into the hands of Ephraim Waite at the time of Obed's death in 1878. Stolen from the Marsh home by servants bribed by young Ephraim. The stolen book was later discovered by Ephraim's father, a devout Methodist, who confiscated the volume over his son's protests. Upon the elder Waite's death a few years later, it was given over to Thomas for safekeeping.