Private Counselor Grotius prides himself on his collection of rare Bibles, but one cheap reprint holds a secret darker than any theology. When workmen in a condemned graveyard are terrified by a skull that appears to move across the earth, Grotius discovers a long steel spike hidden within the bone. To identify the assassin, he need only return to his library shelves. Inside a specific volume, a yellowed bookmark remains exactly where a servant placed it years ago, marking the scriptural inspiration for a perfect, silent murder.