Dutty Boukman's book

Dutty Boukman's book was an object of interest to both the Assassins and Templars last seen in Haiti, November 1791.

Supposedly containing voodoo secrets, the book was confiscated from rebel slave Dutty Boukman by General Rouxel who used it as part of his attempts to get Boukman to confess to his crimes prior to execution.

Among the gathered crowd watching, the Assassin Elsie planned to acquire the book and rescue Boukman but she was talked down by Fabien who had received new orders from the Assassin Brotherhood to allow the execution to ahead and retrieve the book at a later time.

At some point the Templar Order became aware of the book, which prompted the Assassin Charlotte de la Cruz to relive Elsie's memories in 2016 and discover what information within the book was desired by the Templars. However, she was ejected from the Animus early due to a fault and her search was delayed.

Reference

 * Assassin's Creed FCBD 2016 Edition - The Chair