This is the second quest of the game's prologue, which begins immediately after completing "Unfamiliar Lands." During this mission, the Greymanes come under attack by the Black Bears. This quest serves as a tutorial, allowing you to familiarize yourself with the basics of combat.
Once you regain control of your character, your first task will be to defeat a few hostile warriors attacking you.
The closest to you, slightly to the northeast, is Oongka. Approach him, and after a short cutscene, defeat all the enemies.
Naira is located to the north. Head there. Approaching her will trigger another cutscene and thrust you into combat with the enemies. Kill them all.
The last of your companions, Yann, is located slightly to the southwest of your current position, near the river. Head there and, just as before, take out the enemies.
Once you defeat all the minor enemies, Myurdin will appear on the battlefield, and a fight with him will begin shortly after. No matter how hard you try to defeat him, the battle will end in a scripted outcome. This mission will then conclude, and the next one will begin.
The Black Bears' ambush scattered the Greymanes before anyone could count the survivors.