While Mordred was out hunting, his castle has been stolen by 3 lords! They have started building walls after you arrived. Go and reclaim your castle.
Hints are at Mission's briefing.
The map is covered by Tree mazes and you have 2 paths to choose from, 2nd path is to destroy Blue Arthur and
the 1st one is to get to your homeland, Ignore Blue Arthur's castle since it's way too dangerous for your army.