The events of chapter V very much depend on your decisions from Q4.107. Free Elves.
Quest Q5.108. Sweet Revenge is activated once you enter the Dike.
If you decided to support Squirrels in their fight for freedom, you'll get a quest from Zoltan named Q5.109. Hope That Burns. If you decided to remain neutral, Zoltan will give you Q5.124. Under a Fiery Sky. And if you decided to support the Order, Zoltan won't be too talkative, and after a short conversation with him you'll get a quest Q5.126. The Fire that Cleanses.
Regardless of all the above, you'll embark on a quest for Foltest Q5.110. Her Highness the Striga, as well as Q4.95. Armor. Also, more phases of Qp.4. Witchers' Secrets will come to be.
Q5.109. Hope Burns Bright
This quest will be available if you supported the Squirrels in the previous chapter.
Phase 1. Zoltan
Talk to Zoltan. He asks you for help in rescuing the refugees. Head to Old Vizima.
Phase 2. Refugees
You meet Zoltan again in Old Vizima (M33.2).
Phase 3. Another Group
One group of refugees is in one of the alleys (M33.9).
Phase 4. Hospital Bound
The second one is in the parallel alley (M33.17).
Phase 5. The Striga
When you enter the hospital (M33.5), a guard appears saying that the Striga appeared near the tower (M33.21) and keeps killing people.
Phase 6. To Shani
Kill the Mutant near the tower. He was mistaken for a Striga.
Phase 7. Defense
Go back to the hospital (M33.5). After a short talk with Shani an Order Commander will enter and you will have to defend the hospital.
Phase 8. Knights of the Order
When you deal with the knights inside, eliminate the ones surrounding it.
Phase 9. Toruviel's Commando
You meet Toruviel on the outside. Help her.
Phase 10. An Invitation
Follow Toruviel to the hideout (M33.7).
Phase 11. Talking to Toruviel
If you want to have some fun, at the end of your conversation with the commando leader, say that you need to speak with Toruviel. Go upstairs. When you talk to her, just say that her wish is your command.
Phase 12. The Barricade
Leave the Scoia'tael hideout.
Flashback: You now realize that Toruviel came here because you helped her in chapter IV.
Phase 13. Assaulting the Barricade
Talk to Zoltan.
Phase 14. Flanking on the Right
You have to break through the right flank, to the Order's field command post.
Phase 15. Flanking on the Left
Help the Squirrels to battle the knight and go further to the left flank - smash the barricade using Aard.
Phase 16. Yaevinn's Plan
Just past the barricade you have to fight some more. Once you're done with that, Toruviel appears and proposes a frontal attack. Smash the next barricade (M33.24).
Phase 17. The Fight is Won
And after defeating even more troops...
Phase 18. The Refugees Safe
... you'll see a scene in which White Rayla dies and you all leave Old Vizima.