When Langdon's mentor, Peter Solomon - prominent mason and philanthropist - is kidnapped, Langdon realizes that his only hope of saving his friend's life is to accept this mysterious summons.

It is to take him on a breathless chase through Washington's dark history. All that was familiar is changed into a shadowy, mythical world in which Masonic secrets and never-before-seen revelations seem to be leading him to a single impossible and inconceivable truth...