CharacteristicsEditThe ledger was a large leather-bound book with a red cover. It had a red ribbon acting as a bookmark. It was stored in a case to protect it from damage, explaining its near-perfect condition despite being several decades old.
The ledger had information on every experiment that the Thules performed. It also listed the names and the number of people who were forcibly experimented on. According to Sam, the experiments were horrible and performed on the camp's population. Its main content however, were information regarding necromancy, a black branch of magic that the Thules perfected and used on themselves.
The ledger was first located in the headquarters of the Thules in Vitsyebsk, Belarus, until it was lost in the Cloaking Flame that Eckhart cast. Over the years, it was kept in a college library in Pennsylvania, where it was stolen by Rabbi Bass, who passed it on to his grandson.
The ledger was initially created by Thule leader Commandant Eckhart to catalogue his work into creating a successful necromancy technique through experiments on the residents of the Vitsyebsk ghetto. After succeeding in creating a way to bring back the dead, Eckhart listed the names of the Thules he resurrected on the last page as well as his experiments on how to kill those he resurrected once more. In 1944, the rabbis of the Judah Initiative created a Golem to stop Eckhart and he attacked the Thule base in Vitsyebsk. During the fight, Eckhart lost the case containing the ledger and was forced to use the Cloaking Flame spell to flee before he could retrieve it.
While the ledger was generally believed to have been destroyed, Rabbi Isaac Bass, the last surviving Judah Initiative member believed it was found after World War II and spent nearly seventy years searching for it. In 2013, Rabbi Bass finally located the ledger in a college library in Wilkes-Barr, Pennsylvania in the United States and hid it before he was murdered by a Thule named Torvald. Rabbi Bass' murder drew the attention of the Winchesters and his grandson Aaron Bass to whom he had passed possession of the Golem and intended to take up the work of the Judah Initiative. The Winchesters and Aaron located the ledger and killed Torvald when he tried to take it from them. Examining the ledger, which Aaron recognized from his grandfather's stories, the Winchesters learned of Eckhart's successful experiments and how to kill the reanimated Thules permanently. Eckhart, Heintz and two other Thules attack in an attempt to retrieve the ledger, but all but Heintz are killed by the Winchesters. Following the fight, Aaron takes full possession of the ledger in his efforts to complete the work of the Judah Initiative while the Winchesters catalogue a copy they made at the Men of Letters bunker.
Over the next three and a half years, Aaron and the Golem hunt down the Thule listed in the ledger. Using the names from the ledger, Aaron and his Golem are able to kill off half of the known Thule membership.