Murdoch and Crabtree investigate when workmen uncover a body near some former docks. The murdered remains date from perhaps the mid-1860s. A whiskey flask clenched in the man's hands. Murdoch inspects the flask and finds a secret compartment containing what appears to be part of a coded message. Investigations lead to political conspiracies being uncovered and a far bigger case is on their hands than first expected.

While investigating a lethal gunshot on a trolley that no one seems to have heard, Mudoch finds that the disappearance his old girlfriend Anna Fulford may be linked.