Important: this quest will prevent you from being able to do the secondary quest Flesh for Sale, so if you wish to do that first, wait until you get to Skellige and can complete that quest before starting this one.
Go talk to the supervisor, who will reveal that the beast is already being hunt down by a "brave fool" that turned up, additionally he'll tell you the location of the incident.
After examining the crime scene, follow the track of claw marks until you reach the river, here you have to swim to the other side, were you'll find the rest of the tracks. Upon entering the building you'll find Lambert fighting the Ekimmara, after the fight you can loot the body for an Ekimmara hide.
Then go to the supervisor, were Lambert will start a fight, you'll have to kill three guards and then go talk to Lambert. No matter what he'll finish off the supervisor and ask you to join him at the Seven Cats. When you find him, Lambert will explain that he's after an assassin named Jad Karadin in order to avenge for Aiden, his witcher friend from school of the cat that Jad and his gang murdered.
When you talk to Vienne, she will claim she doesn't know where Jad Karadin is. However, she will provide you with the information of the other two members, Selyse and Hammond. A fight may or may not break out depending on which conversational option is chosen at the end. Choosing the option "Do what you think is right" will cause Vienne to call for help. The conversation ends, and Geralt enters combat with Vienne and three other elfs. On the other hand, choosing "Don't kill her" will cause Vienne to insult Geralt, but no fight breaks out. In either case, Lambert will suggest splitting up, where you will search for Hammond in Faroe.
Hammond can be found at Trottheim or a shrine east of there depending on whether you complete Flesh for Sale or not. After a brief dialogue with him, he and his men will attack you. Once all of them are killed, searching his body will give you a letter from Jad Karadin.
- While wallowing in the Bits, Novigrad's worst and most notorious slum, the witcher took a contract on a monster committing horrendous murders under the cover of darkness. At the time, he never suspected that a story starting in the gutter would end in a luxurious manor.
- Near the Novigrad docks Geralt ran into his old brother at arms, Lambert. Geralt's surprise grew when he realized the ekimmara they both were hunting was not the chief reason for Lambert's presence in the city, But before they could sit down for a heartfelt chat, the two witchers had to deal with their dishonest contractor. How many times will men try to cheat witchers out of honest pay for honest work before they learn...? That taken care of, Geralt could now talk to Lambert. It turned out that he was hunting the people responsible for the death of his friend, Aiden, a witcher from the Cat School. Lambert had learned Aiden had been murdered by a gang of hired thugs led by a man named Jad Karadin. Geralt decided to help Lambert and the two set off on a path to revenge.
- It turned out the monster was an ekimmara, but that was of minor importance. What was truly interesting was that Lambert was hunting the creature as well. And most interesting of all was that he was doing so in order to get to the leader of a group of assassins who had killed his friend. One by one our heroes hunted down the members of the group until they had finally found their boss – Jad Karadin.
If Geralt lets Jad live:
- In the end, Lambert and Geralt found this Jad Karadin. When they did, they were in for some serious surprises. The man was in fact a retired witcher, now living in the lap of luxury, surrounded by his beautiful... family? But how? While there was nothing surprising about his wife, Leticia, the last thing Geralt expected to find the home of a sterile witcher were two bright-eyed children. It turned out the kids were adopted, and Karadin swore he loved them as if they were his own. Karadin convinced the witchers he had changed for the better and set aside his killing ways. Hearing this, Geralt told Lambert to abandon his plans for vengeance. Did he do right? That, dear reader, is not something a chronicler scribbling the tale down in a comfortable alcove with the benefit of hindsight is in a position to judge.
If Geralt kills Jad:
- In the end, Lambert and Geralt found this Jad Karadin. The man was living in the lap of luxury and would have blended in perfectly amongst the cream of Novigrad's crop – had he not been a witcher from the Cat School. Quite unexpectedly, Karadin welcomed them into his home and introduced them to his wife, Leticia, and his two adopted children.
- Over the course of their conversation, Karadin tried to do the impossible: convince two trained killers bent on his death to let him live. He said he was a changed man and had sworn off his assassin ways. Yet his repentance had come too late, and he paid for his past crimes with his own blood.
- Talk to the supervisor.
- Examine the crime scene using your Witcher Senses.
- Find the monster that is prowling the area by using your Witcher Senses.
- Find the place where the monster emerged from the water by using your Witcher Senses.
- Find the ekimmara's lair by following its tracks using your Witcher Senses.
- Look for the ekimmara in its lair using your Witcher Senses.
- Kill the ekimmara. (50)
- Talk to Lambert.
- Defeat the guardsmen.
- Talk to Lambert.
- Meet Lambert at the Seven Cats Inn. (80)
- Go to Faroe and look for Hammond.
- Ask Crach what he knows about Hammond.
- Find Hammond.
- Find the shrine where Hammond prays.
- Kill Hammond. (? )
- Search Hammond's body.
- Meet Lambert at the Nowhere Inn.
- Meet Lambert on Hierarch Square, near Karadin's residence. (90)
- Decide Jad Karadin's fate. (4 if spared)
- Kill Jad Karadin. (If not spared)
- During the fight with Vienne one of the combatants could get himself stuck outside the inn, and Geralt cannot reach him due to him being in battle stance, forcing you to reload a previous checkpoint.
- The location marker can sometimes incorrectly show Hammond in the center of Trottheim, depending on whether or not you have completed Flesh For Sale. In this case, Hammond can be found at the shrine near the most eastern point of the island.
- The Main Quest Destination: Skellige must be completed before being able to complete "Following the Thread" in order for Geralt to access the islands.
- The quest Flesh for Sale will become unavailable if you have not completed it before you speak to Lambert at the Seven Cats Inn.
- Retrieving Uma during Ugly Baby will cause this quest to fail.