1. Ask Crach an Craite about Hjalmar.
When talking to Crach an Craite, ask him everything you can about his son.
2. Ask around at the New Port Inn about Undvik and the Ice Giant.
Head to New Port Inn and talk to Tante or Javor. They'll tell you how to get to Undvik. You can also talk to Axel, and Jonas the Inkeep.
3. Sail to the island of Undvik and search for Hjalmar.
Sail to the island. If you have bought "The Lonesome World Guide to Undvik" map from the Merchant and you already have an active "Marlin Coast" signpost on the island, then you can use the fast travel option.
When you get to the island, you'll receive a new objective of reaching the ruins of Urskar.
4. Explore the boat's hull. / Talk to the stranger.
On your way to the ruins, you'll have to walk past the wreck of a large ship located in the middle of the island. There you will see a huge giant feeding sirens and someone in the hold of the ship.
When the giant is gone, kill the sirens and enter the hold of the ship and you will meet Octo there, who will tell you a little bit about Hjalmar. if you spoke to Axel back at the New Port Inn then you can discover his true identity - he is the jarl.
At the end he will ask for some Twine and Nails (quest items).
You can find the nails that Octo needs near his boat (north of it). Bring him the items he needs before the quest is over and you will get additional XP.
You can also find the nails at the Dorve Ruins where you meet Hjalmar.
4.1. Find Hjalmar's camp. / Explore the remains of Hjalmar's camp using your Witcher Senses.
Head to the Hjalmar's camp and examine the bodies in the camp. Geralt will conclude that he should search the area around the camp and then you will be able to find two more tracks...
...footsteps of two people...
...and tracks left by a boat being dragged.
4.2. Use your Witcher Senses to follow the tracks of those who fled the camp before the attack.
Follow the footsteps of those who fled the camp before the attack. Along the way you will come across a nest of a nekkers and a dead nekker there, then two more nekkers killed by a bow arrows and finally you will reach the Abandoned Village. In the village you will find plenty of blood traces and more footprints that will lead you to the entrance to the Ice Trolls Cave. There you will find the corpse of one of the men you are tracking and the Hornwall horn lying near the body.
Examine the footprints in front of the entrance to the cave.
4.2.1. Find the man the trolls captured using your Witcher Senses.
You'll come across ice trolls (19) in the cave. You can kill them, but you can also bypass them. You have to get to the cave where the two trolls cook something.
In the cave where you meet the first troll, turn right into the corridor leading north.
Then turn into the first corridor leading to the left. A little further, Geral should comment that he can feel that something is cooking nearby. When you reach the exit of the cave, you will be able to climb the rock shelf on your left. This corridor will lead you to a cave where two trolls cook something. You will be able to talk to those two.
4.2.2. Help the man in the cauldron. / (Optional) Defeat the trolls.
The archer you're looking for is in the cauldron. The trolls want to make soup out of him. You must convince the trolls to free him. You can do this in two ways: kill all three trolls (18) or solve their riddle - the correct answer is "troll". If you choose the wrong answer, the correct answer to the second question is "rock" If you make a mistake twice, the man in the cauldron will die.
The archer's name is Folan and he is Hjalmar's companion. You will learn from him that Hjalmar was going to cross the lake. After the conversation he will join you and help you with his bow. You will also be able to meet him again in one of the next quests.
Geralt set out to find Hjalmar an Craite, but first came across the lad's companion in arms, a man by the name of Folan. Folan told the witcher that Hjalmar's crew had scattered when the giant attacked. As for the fate of Hjalmar himself - that Folan could not tell him.
4.2.3. Cross the lake.
Talking to Folan will cause a new marker to appear on your map, suggesting that you visit the Dorve Ruins area. The easiest way to get there is by walking along the lake or swimming. You can also go through the cave, but it is a much longer and harder way.
4.3. Follow the boat trail using your Witcher Senses.
The boat trail will take you near the lake, where you will find the broken boat itself and the corpse of another of Hjalmar's comrades near it.
5. Explore the ruins of Urskar and search for signs of Hjalmar's presence using your Witcher Senses.
In the village of Urskar you will find the bodies of several of Hjalmar's comrades.
5.1. Find out what happened to Hjalmar's crew.
Go to Urskar and examine the signs of the battle.
5.2. Follow the trail of blood using your Witcher Senses.
Follow the tracks until you reach the Harpy Cave entrance.
5.3. Find out what happened to Hjalmar's crew in the caves.
You need to get to the other Harpy Cave entrance. Get inside and jump down into deep water. Find a place where you can climb up and continue on the rocks and ladders. Along the way you will find the corpses of more Hjalmar's companions. In the cave you will come across various monsters such as erynias (13) or devourers (13).
6. Find Hjalmar. / Help the stranger drive off the sirens.
If you have chosen a way through the cave, then you will exit it near the "Clan Tordarroch Forge" signpost. Get into the building. You'll find the bodies of another Hjalmar companions there. At some point you will notice that "something" has run out of the building through the other entrance. Examine the footprints and follow them. When the tracks split, go left and you will reach the Dorve Ruins.
No matter which way you choose - through a cave or along a lake, you will find Hjalmar in the Dorve Ruins where he is fighting a few sirens (13). Help him defeat them.
Geralt searched every inch of Undvik until he finally came across Hjalmar near the giant's lair. Hjalmar had journeyed there to free Vigi, one of the members of his crew. As he deemed the cause a worthy one, Geralt decided to lend Hjalmar his sword.
7. Find a way to the giant's lair.
Follow Hjalmar to the Giant's Lair entrance. In the cave you will come across a sleeping giant and one of Hjalmar's companions - Vigi, locked in a cage. No matter what you say about his releasing, you will be able to do it.
8. (Optional) Find the key to Vigi's cage using your Witcher Senses. / Free Vigi.
Note: Do it if you don't want Vigi to die. If you save him, then you will be able to meet him again in one of the next quests.
Approach the chest on the other side of the cave and take the Key to Vigi's cage from there. Avoid snow, becouse the sound of it crunching under your feet will awake the giant. Then go back to Vigi and open the cage. Once you do that, Vigi will attack the giant and the fight will begin.
9. Kill the giant.
The fight against the giant consists of two phases. In phase two, the giant will attack you from a greater distance with a ship's anchor.
After the fight you will be able to choose whether you want to stay in the cave or go to the Marlin Coast village with Hjalmar. In both cases the quest will end.
Helping Hjalmar an Craite did not prove easy. Undvik had gone feral after the ice giant drove its inhabitants away, with monsters running amok on the island as though it were some mad mage's experiment or a misguided entrepreneur's attempt at an innovative hunting preserve. Yet in the end the witcher triumphed, not only finding Crach's son, but also helping him kill the giant and avenge the men the beast had murdered. His heroic deed accomplished, Hjalmar could now leap out of the starting blocks in the race for the Skellige crown.
