New Main Quest: Travel with Samuel the Boatman to your first mission (
New Main Quest: Take the blackmail journal from High Overseer Campbell
New Optional Quest: Ensure Captain Curnow survives his visit to the Office of High Overseer
Exit the building and go towards docks. On your way there you should be stopped by Callista and asked by her to save her uncle Geoff Curnow, who is the captain to the watch, from death.
Go to the docks and start your conversation with Samuel. Confirm your will to set out to a new mission (the upper-right dialogue option).