As mentioned in the other solutions, turn the difficulty right down if you haven't already as it will make your life a lot easier. I also tend to save regularly as well so that if you do make a mistake or get into trouble, you can reload without having to go too far back.
To obtain this achievement, you need to complete 3 quests, two of which are part of the third. The main quest is Understanding Madness and its two mini-quests are Lady of Paranoia and Addiction.
When you have finished speaking to Sheogorath about the previous quest, he will give you the ability to summon Haskill for 5 seconds. You have to test it out for him before talking to him again as he refuses to continue conversation. I performed the spell a couple of times (in fact, the only times I ever used it) and then talked to Sheogorath once again. He tells you to talk with each of the court's rulers.
It does not matter who you go to first but I went to see Syl (of Dementia).
Talk with Syl and she will give you the title of Inquisitor as she feels there is a plot against her and wants you to get to the bottom of it. You can speak with her about Herdir (her torturer) and then go and find him. You can the use Herdir to torture answers out of people (quite amusing). Speak with Kithlan, her steward, to try and get some information out of him. When he tells you more (thanks to Herdir), you are then directed to Anya Herrick. With some encouragement
, she then says about Ma'zaddha being involved. Ma'zaddha doesn't respond to the same treatment though so you have to try it on another villager who will then inform you that Ma'zaddha has been meeting with Nelrene in the dead of night. At about midnight to half past, the two will meet near Ma'zaddha's house (Nelrene gets there first). You can listen from above to the conversation that the two are having. When they finish up, confront Ma'zaddha after Nelrene has gone and he will confess to the conspiracy. He says to meet him 24 hours later at his house. I just went ahead and waited 24 hours from then and went into the house. Upon entry, I found him dead in the main room, I looted his corpse for the house key and went upstairs. In the upper room, you will find a ceremonial sword and a note from Ma'zaddha, pick these up. You can then go and find Nelrene who informs you that Muurine is the leader of this little plot. Finally, head to Muurine and she will confess to this treachery. Now, you can go and tell Syl the news. Speak with the Duchess and then go and witness the execution. First mini quest done.
Time to go and see the Duke of Mania, Thadon. Speak with him and find that he asks you to find the Chalice of Reversal for him. If you speak with Wide-Eye, his stewardess, and she will add the marker for Dunroot Burrow to your map. If you have discovered a location near it, then you can fast travel as close as you can but if not, once again, I am afraid you will have to hump it all the way. When you get into the area, you will get these spider things (Elytra) attack you. Kill them and check their bodies for Felldew. One of them, probably one very close to the entrance, should have it and by eating it, you can then access the burrow. You cannot go through the entrance door without eating it. You then need to work your way through the burrows killing the Elytra as you go. Every so often, you will come across one that is glowing green; this will have Felldew in the corpse when you check. The Felldew wears off after a while and you go into withdrawal. Eating more Felldew obviously stops the symptoms. I found that you could deal with a lot of withdrawal before actually having to eat the Felldew. After working your way through the burrow for a while, you will see that the marker on your map points to a door but the path is blocked by branches. There is no way to get through them and you have to keep working your way around the paths to finally get to this door. When you go through the door, you get a notification telling you that you have made your way through the maze of burrows. Upstairs in the room, you will find 3 addicts. Kill them (they only use their fists) and then pick up the chalice right in the middle. This will reverse all the Felldew effects. There are also some beds you can use if you need to sleep for whatever reason. Follow the marker out of a different door to which you entered and then fast travel back to the castle. Speak with Thadon to complete the quest.
4 out of 10 achievements done!