Word of your deeds in Grizzleheim has reached the ears of the greatest of the ravens, none other than Grandmother Raven herself. She's calling you to rescue her from the Coven....
You will begin your journey in Wintertusk after you have completed the "Blood Brother" quest in Grizzleheim. If you have completed this quest, speak to Merle Ambrose who will give you the quest "Cold News". If he does not have the quest 'Cold News' for you, have haven't completed the "Blood Brother" quest.
When you begin your quest to rescue Grandmother Raven, you will be sent to Hrundle Fjord, the main zone in Wintertusk.
Hrundle Fjord is a small walled Viking-style village, primarily inhabited by bear warriors and traders. There is a small dock outside where merchants and warriors enter the zone. It’s remote and cold, perpetually covered in snow, and it’s among the older places in Grizzleheim. The surrounding zones are full of wild creatures and barbarians.