The Witcher 3: Wild Hunt has a major campaign that takes on average about 40 hours to complete. Amid the many challenges faced by the protagonist Geralt, you can end up losing in the midst of so many tasks. An example is the mission "Family Matters", where the Bloody Baron asks Geralt for help to find his wife. To solve this mystery, check out (no spoilers) the following step by step guide:
Step 1. After the flashback with Ciri mission "Family Matters," the Bloody Baron asks Geralt to help him find his wife and daughter Tamara. While the two tasks remain active at the time, still cannot find the wife of Baron. Thus, focus on travel to Oxenfurt to find his daughter;
Step 2. Once you find and talk to Tamara in Oxenfurt, Geralt continues without direct clues leading to the wife of Baron. So, complete the quest "Hunting a Witch" (if has not already done) to release the "Ladies of the Wood" mission. Then head for the Twisted Marsh to start it;
Step 3. During the "Ladies of the Wood" mission Geralt will be asked the magistrate to investigate a tree possessed by a spirit. After finding the heart of the tree and make a decision, just return to talk to the Fates in the Swamp and finally discover the whereabouts of the Bloody Baron’s wife.