A Tome Entombed Witcher 3: Wild Hunt Quest
Suggested level: 13
Group: Secondary Quests
Location: Novigrad
You can start this quest by finding Professor Vairmont a.k.a. Gustavo in the crypt which can be accessed through the sewers in Novigrad. These are the same part of the sewers that you explore during "A Dangerous Game" quest while chasing Duke, so it is best to do these two quests at the same time.
While in the passageways underneath Novigrad (I've been there as well, and don't recommend them as tourist destinations - if the stench doesn't get you, the monsters will) Geralt met a scholar who was excavating in search of traces of long-lost cultures. The professor asked Geralt for help removing the lid from a certain ancient sarcophagus.
While chasing Duke, since you don't have to hurry, before you approach Duke and start talking to him, you should turn to one of the nearby tunnels and find another wall to destroy.
On the other side of the wall you will find the crypt and Professor Vairmont.
Another way to get into the sewers is to enter the tower next to the Tretogor Gate. Then you should walk along the corridor to the neighboring tower and go down the ladders there.
Related points of interest
Professor Vairmont
Velen / Novigrad
Quest stages of A Tome Entombed
1. Return to Professor Vairmont if you want to help him with the sarcophagus.
The professor is an archaeologist and will ask you to help him open a sarcophagus which, to his knowledge, should contain a valuable manuscript. You can refuse, but it won't end the quest. You'll have to return to the professor one day and help him anyway.
When you open the sarcophagus, you will find a vampire in it. When he finds out that you woke him up in the wrong year, he will lock himself in the sarcophagus again to sleep.
The professor will ask you to open the sarcophagus again because he hasn't had time to look at its contents. You can refuse, but the quest will still be active and you can come back here if you change your mind.
2. Kill the vampire.
When you decide to reopen the sarcophagus, you will make the vampire angry and he will turn into a Katakan (11) and attack you. When you kill him, the professor will thank you for your help, although he'll be a little disappointed he couldn't talk to the vampire.
Geralt decided to promote the advancement of knowledge and help the scholar open the sarcophagus. Instead of the expected withered skeleton, inside lay a fully fleshy vampire. He was not hostile at first and merely asked for a bit of peace and quiet while he finished his rest. The scholar, however, had no intention of respecting this wish. Geralt could not stop him and... the vampire lost his temper and attacked Geralt and the bothersome professor. Whether he wanted to or not, Geralt now had to end its life.