Keep Durk bound, take him back to Foxglove for trial (and likely gibbetting) and to update them on what has happened. You can prepare for your next step (Amberlake, Morgan's Hollow, Brother Owen, back to the caves, etc.) once there.
Let Durk go. Return to Foxglove to update them and to prepare for a trip to Amberlake or Morgan's Hollow.
Let Durk go. Head on to Brother Owen's from here.
Let Durk go. Inspect the cave and surroundings to learn more about these visitors.
Recruit Durk. If this selection wins, then Durk will join the group, which will take the action of the most popular of the "Let Durk Go" options, above.
Some other creative option? (please comment)