Brynjolf informs you that someone named Maven Black-Briar, the influential contact for whom you undertook your previous mission, wants to talk to you about a job. Head out to the Bee and Barb, where you’ll find Maven on the second floor of the inn. She would like you to investigate an up-and-coming meadery called The Honningbrew Meadery.
She sends you west, to Whiterun, to meet with her contact in the Bannered Mare, Mallus Maccius. Mallus cooks up a plan to poison their brewing vats and knows of a way you can get inside the place, for the owner has a bit of an infestation problem that has to be dealt with by an able body.
When you’re done talking, Mallus sends you to Sabjorn himself. Head to the Honningbrew Meadery, talk to him, and offer to help him with his infestation problem. He’ll eventually agree, so take it upon yourself to purge the place of Skeevers, Frostbite Spiders and any other creatures infesting it. If you can successfully [Persuade] or [Intimidate] Sabjorn during your initial conversation, he’ll give you a half-payment of 500 gold up front.
When you get close to the nest of the infesting creatures, you will encounter a madman named Hamelyn, a disgruntled alchemist who is breeding a Skeever army with which to exact revenge on the people whom he perceives to have wronged him in the past. Hamrlyn has a very powerful magic attack that can make this a tough fight. Try your best to avoid getting hit by his attacks and dispatch him as quickly as you can. Don’t hesitate to use potions to increase your various resistances or your dragon shouts to attack him with if you find yourself struggling.
Once the fight is over, apply the poison to the nest and proceed into the basement of the brewing room. Go upstairs and activate the lid on the marked pot to apply the poison to the brewing vats. Now grab the key beside the door and depart.
Talk to Sabjorn and he’ll say your payment will have to wait until after the captain leaves. When the Captain tastes the mead he will arrest Sabjorn. After they leave, talk to Marcus who will give you the key to Sabjorn’s office to find the information that Maven wants.
Go upstairs and find the promissory note. There is another item here that is worth taking, the Honningbrew Decanter, for the reason that you can sell it to Delvin for a good price. Talk to Marcus again and he’ll offer to be your fence in Whiterun from now on.
Return to Maven back in Riften and give her the information you found. She relays the information back to the Guild, so speak to Brynjolf to complete this quest.