Geralt goes to visit this man name Olgierd, who posts a bounty to kill a monster in the sewers
He kills this monster (a giant toad), who transforms into this man, and Geralt gets captured by that man's associates and taken aboard their ship as prisoner
While on the ship, a mysterious man name Gaunter O'Dimm (he actually appears at the beginning of the original game) shows up and frees Geralt, but asks a favor from him and burns a mark into this face
Geralt goes to meet Gaunter again, who tells him that Olgierd made a deal with him for 3 wishes, in exchange for something personal
So Geralt goes back to Olgierd, who says that the giant monster was a man who had been betrothed to his wife, but out of jealousy he cursed him into the monster
anyway, not that important. So Gaunter shows up and they talk about the 3 wishes: give Olgierd's (dead) brother the time of his life, bring Olgierd the house of a banker named Borsodi, and bring Olgierd the rose of his dead wife Iris
So Geralt goes out and completes these tasks. While doing so, he learns about Olgierd, that he was once a wealthy man, but his family became super poor and his wife divorced him and became betrothed to the toad man
Then somehow, he reacquired his riches and his wife, but his heart turned to stone and he lost all feelings of love and also became immortal
After these tasks are completed, Gaunter asks Geralt to see him in private, and Gaunter pulls a crazy trick by stopping time. He then asks Geralt to meet with him and Olgierd at a temple
In the meantime, Geralt goes to seek out a professor who had done research on Gaunter, and he reveals that Gaunter is actually Evil itself, who makes pacts and grants wishes to people, in exchange for their souls
The prof tells him there's no way to kill Gaunter, but he can be beaten on a mental level
So Geralt goes out to the temple, where Gaunter talks about how all of Olgierd's wishes have been fulfilled, and the final clause is that he will take Olgierd's soul when they are standing on the moon. And they are standing on a graphic of the moon at the temple
As Gaunter goes to take Olgierd's soul, Geralt can either intervene, or let Gaunter finish the deed
If Geralt intervenes, he challenges Gaunter and bets his soul to save Olgierd
So Gaunter gives Geralt a riddle to solve and puts him inside this hell-world. Geralt goes around and eventually solves the riddle ("reflection") by busting a wall and causing water to pour out, allowing him to see a reflection
Are u done

So Gaunter leaves and Olgierd becomes mortal again and feels all the regret that had built up to that point and vows to rebuild his life
I need to know when I can start reading lol

One last bit
If Geralt chooses not to intervene, then Gaunter will take Olgierd's soul. In exchange for Geralt's services, Gaunter can grant him a wish, or just give Geralt some tips on Ciri (and actually gives hints on how to get the good ending of the original game lol)
Ok I'm done. wew lad