You can’t reach Gibbet Woods to the north until you’ve dealt with the Minion Dreadwing in the area. Track it down using the Gold Quest Marker on your mini-map, dealing with its fellow Minions on the way. Note that crafty Ranged specialists can use the area’s plentiful supply of explosive barrels to do extra damage from a distance.
As the path opens out, enter the cottage on the right—saving the Guard here gives you another ally in battle. Back outside, continue up the hill then head east to deal with the Minion Dreadwing near the windmill. Once it’s taken care of, you can finally make your way north. Oh, and watch out for the assassin if you had a hit placed on you back at Knothole Glade!