Notice! You can follow Roche's path, if during Act 1 you chose At a Crossroads: Vernon Roche.
Step 1: Go to the gates of Loc Muinne
You will begin the third act on a mountain path leading to Loc Muinne. Keep going down, eliminating Harpies on your way. Right before the city entrance, you will notice the Knights of the Flaming Rose (M31, 1).
Step 2: Go to the audience with king Radovid
Notice! If during Witcher 1 you sided with the Order, you will be able to approach the knights and talk with them - they won't do you any harm. If on the other hand you sided with Scoia'tael, you will be attacked.
If you didn't import your game, you can go talk with Radovid without any problems. Follow Roche to the city. He can be found by the pillars (M31, 30), in case you decide to take a look around.
When you're ready, let Roche know and you will go meet with Radovid. If during the second act you have killed Henselt, you will be asked about those events - it doesn't matter whether you take responsibility or blame your companion. You can also use persuasion to avoid giving a proper answer. In order to continue the conversation, go out of Radovid's camp. You will have to make a very important choice:
You decide to save Anais
Prize: 500 XP
You will unlock Of his Blood and Bone.
You decide to save Triss
Prize: 500 XP
You will unlock Where is Triss Merigold?. Description in [ act 3 - main missions - common ].