At a Crossroads Scoiatael, is the quest you have to complete in Witcher 2 Enhanced Edition, if you decide to continue the game with Iorveth by your side.
This quest affects the events that occur in the following chapters, as well as all main-quests and side-quests you will be able to complete.
If you think that Iorveth is the right choice instead of Vernon Roche, you will have to finish this quest.
Geralt was on a crossroads. He had to save Triss Merigold, yet he was incapable of handling this problem alone. The witcher needed backup a fact he knew all too well. After our discussion, it turned out he can ask either Vernon Roche or Iorveth.
Cooperation with the Squirrels excluded good relations with the Temerians, and on top of that Iorveth had to be freed from a floating prison first. Geralt went to make his choice. But did he choose the Scoiatael?
If you are in Flotsam, your first step is to meet Zoltan in the elven ruins. Travel south and follow the path that takes you above the waterfall (where you found the Rose of Remembrance).
Talk to Zoltan and choose your next ally.
Note: From this moment , there is no turning back, and if you change your mind regarding Iorveth, the only way to switch sides, is to load the file you have saved (assuming you followed our previous walkthrough), or to play the game from the beginning.
Once you confirm that you wish to help the Scoiatael, Zoltan will reveal his plans. At a Crossroads Scoiatael ends after Zoltans dwarves tell you to meet them by the river bank.
Since you sided with Iorveth, you will fail to complete At a Crossroads: Vernon Roche quest and you will begin the next quest in line: The Floating Prison.