The Salesman's Ledger is a mysterious, powerful book, that once belonged to the multiversal power-broker called The Salesman, and has even been described as an "extension" of its former owner. It has been taken by Joseph Chamberlain, a former agent of the Salesman, and is used by him and his sister in an attempt to track down the mysterious entity.
The Ledger's pages are almost magical, serving as text or a map depending on who looks at it, as well as when and why. It actively resists being read by anyone but the Salesman, rearranging letters and moving words. 
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