The Cog is a type of ship that was used in the middle ages for trading and transport. These ships caused a grow in trade between several european cities and made the Hanseatic League prosperous.
After the king of the forest's secret hideout was discovered by the king's scouts (see my secret hideout entry for last year's CCC), the fortress was attacked and the outlaws inprisoned in a nearby castle.
Now the rest of the outlaws try to free their king with the help of a spy among the castle's guards and a barrel of good wine...