This quest can only be received by finding the letter in each chapter, where do you get the markers if you don't receive the quest?

First of all, what chapter are you in right now? If you are in the first chapter, this quest has not been completed, it means that you have not done the last step of the first chapter, that is, in the Roledo mansion inside the mailbox (unethical plan, after the end of the infiltration or failure, and Roledo conversation with the end of the mailbox near the house to read the letter

If the first chapter of the quest is completed, the letter to the second chapter can not be continued, the other shipwrecked ship in the second chapter

This letter is inside the wrecked ship

The letter is in the second chapter of the quest. >This letter is inside the shipwreck, the location of the shipwreck is in the elf route with trolls at the end of the road (that is, the last step of the dwarven dream killings to go there)

Elf Route: you can go at any time, it is just to go to the valley of the sphinx bird, there is a fork in the road, turn around there are trolls, go to the end of the road, then you're right

Blue Coat Route: you can go there only at the end of the chapter (there is only one chance to go there), it is after the camp massacre, it is the first time to go there. After the massacre at the camp, you have to go to Henset to find trouble, bypass the battlefield and go through the path, and that's exactly the path where you encountered the female trolls for the first time, that's where the shipwreck is located (there's another time when you went to the elven city to look for something, but that time, the path was blocked and you couldn't go through it)