Envoys, Wineboys - Velen (Blood and Wine)

This quest begins off of most Velen Notice Boards if you have the Blood and Wine Expansion, accept the notice that says "Appeal to Geralt of Rivia". Once you have this quest head over to the Stonecutter's Settlement in northeastern Velen (just south of Oxenfurt). When you approach the villagers you'll get a scene with two people that know Geralt.

During this scene you'll have the opportunity to help them defeat some bandits that are harassing the villagers (pictured above). Agree to help them out which will advance the quest forward and after a few scenes, put you into some dialogue with the bandits. No matter what you choose during this dialogue it'll end in a fight with the bandits.

Once the bandits are defeated the two soldiers from Toussaint will tell you their actual request and reason for searching for you. Basically, they want you to kill a monster for them - one in Toussaint. The person issuing this contract is the ruling duchess of Toussaint, Anna Henrietta.

Agree to help the two knights and you'll depart for Toussaint. When you arrive the next quest in the chain, The Beast of Toussaint will automatically begin. Additionally, the next time you gain control of Geralt you'll be thrown into a boss battle.