Not available until after you have completed the quest Contract: Deadly Delights.
Quest starts outside of the Crippled Kate brothel in Novigrad where you come across a crying courtesan. Turns out Skelliger warriors have taken over and are having a party inside the brothel. The courtesan and her friends are willing to pay to have you evict the warriors for them. When you enter the building you start a cut scene where you start talking to the lead warrior.
You have three options, but you can't use your weapons, potions, or any Signs during this quest.
1. Offer to fist fight the lvl 15 leader 1 on 1, if he loses they leave. Not too difficult, just counterattack once to break his combo then keeping pounding away till his stamina runs out. After that he stops blocking your attacks and it's an easy victory.
2. Threaten the group and fist fight all 3 of them (2 lvl 1 warriors, 1 lvl 15 warrior) at once. They can be a challenge to beat seeing as they're all rather large and it's a small area to fight in. I suggest plenty of dodging and blocking keeping your back to the open room to escape for a small reprieve.
3. Use Axii to convince them to leave for an 40 extra experience
Exit the building and the courtesan is where you left her. Talking to her she expresses her gratitude and she offers you your reward. You can choose the gold pieces, or you can refuse payment.
You get the same payment of 25 exp and 15 crowns for each method of dealing with the warriors. But if you refuse payment you still get 25 exp and 15 crowns.