Questions and Answers is one of the main quests in Kingdom Come: Deliverance. It becomes available after dealing with the bandits in Pribyslavitz. Henry must reach Merhojed and interrogate a prisoner. However, things will get complicated - a mysterious pestilence has spread throughout the entire village. Henry can try to heal the villagers (during a side quest) or he can focus on getting information from the prisoner.
Note - Be sure that Henry can read before you start this quest. This is very important if you want a happy ending for Merhojed. Henry can learn how to read during Mightier Than the Sword side quest - meet with the scribe in Uzhitz. The description of that quest can be found in the section dedicated to walkthroughs for Uzhitz's side quests.
Note - Another thing that can help you solve all of the problems in Merhojed is to buy all necessary ingredients before the quest starts. Get 1 Valerian and 2 Thistle from any of the herbalists and 1 Charcoal from a blacksmith.
Journey to Merhojed
Reach the Upper Castle in Rattay and meet with the lords. You receive an order to interrogate a prisoner in Merhojed. Go to that village. Upon reaching it you learn that it is deserted. Speak with any of the villagers that you come across. Henry learns about a spreading disease. This unlocks Pestilence side quest.
Meet with Matthias before you do anything in the village. The man lies on the ground inside of the barn (see the picture). Speak with him about every topic. You learn more about the prisoner and about the pestilence.
You can now act in two ways:
Start doing Pestilence side quest (its description can be found in the section dedicated to side quests) - This is definitely a better idea. Successfully completing all objectives in this quest will allow you to heal everyone (including the prisoner). However, this outcome isn't guaranteed - some of the characters can die if you make a mistake or when you are too slow.
Ignore Pestilence side quest and focus on the main quest instead. This isn't a recommended variant. It can lead to many deaths and/or it can lower your reputation in Merhojed if you try to reach the prisoner by using force.
Reach the prisoner
The prisoner is kept in the barn presented in the picture. In default, that building is guarded by one watchman. He won't let you in even if you invoke Radzig (you can't use any of the unique dialog lines either). Here are the possible solutions to this problem:
Complete Pestilence side quest. Meet with Melichar after healing everyone in the village and ask him to give you a chance to speak with the prisoner. The watchman disappears and you can enter the barn without any problems.
Wait for the pestilence to reap its bloody harvest. You can wait a few days and let a lot of the villagers die due to the disease.
Try to reach the prisoner during your first visit in the village. This variant isn't recommended. The watchman won't leave his post which means that sneaking past him is impossible. The only way is to kill him - attack the man when no one is looking at you. You can also try to perform a quick execution, e.g. by shooting him with an arrow in the head.
Get information from the prisoner
Your main goal is to get access to the barn with the prisoner kept inside of it. The situation here can have one of the three outcomes:
Completing Pestilence side quest cures the bandit. Thanks to that you can interrogate him extensively. You don't have to rely on the unique dialog lines. Simply select all of the options and you will get everything from him.
The bandit can die if you made a mistake during Pestilence side quest or you have wasted too much time on searching for the cure. Search his corpse and take the Captive's letter.
You have managed to enter the barn right after reaching Merhojed (without starting Pestilence side quest) - the bandit is in a very bad shape which means that you can't get any information from him. You can, e.g. finish him off and get the Captive's letter.
The first variant described above has another additional cut-scene that is played after you are done with interrogating the prisoner. Straw runs into the barn and he want to kill the prisoner to avenge his son's death. You can:
Stop Straw from killing the prisoner - This is easy to do. Straw has no persuasion points so select a dialog line connected to it.
Attack Straw - This is a bad variant because you will kill an innocent person. By doing that you will worsen your reputation in Merhojed.
Let Straw to kill the bandit - You won't lose anything here because you already have all the information.
Henry can take the alive bandit to the prison in Rattay.
Give your report to Radzig
Radzig can be found around the vantage point near Talmberg. Speak with the man and give him your report. This completes the quest. You receive 175 Groschen as your reward.