Alhaitham’s story quest continues with A Thorough Investigation, as you and Alhaitham join forces to investigate the mysterious Siraj and his experiments and the mystery of Ilyas’ missing memories. To start this quest, you must have completed the previous quest in his questline, “Fragmented Testimony.” This quest will begin once you reach the Research Preparation Center.
Related: Genshin Impact – Fragmented Testimony quest guide
A Thorough Investigation quest walkthrough — Genshin Impact
Ilyas directs you after remembering two things he had to do, collecting his pay at the Research Preparation Center being the first of them. Head to the Research Preparation Center to get Ilyas’ pay, continue with the questline, and learn more about Ilyas’ past.
You’ll learn that Ilyas’ disappearance has caused problems for the Research Preparation Center. Ilyas will try and make amends to see if there’s something he can do to fix things. The NPC Makesh recommends you visit a man named Chandra to see why the latter withdrew his off-site research application. During this stage, Ilyas will remember a little bit more about the experiments.
You learn that the Akademiya’s atmosphere has been “afflicted with strangeness in recent times.” Chandra points you to a scholar named Janaki, who also received an invitation from Siraj before. Head to Janaki to pursue this lead. Here is her location:
Janaki seems quite upset at Ilyas, ominously hinting at something he has done. She refuses to elaborate, stating it may be for the better, and she leaves without explaining anything. Ilyas wishes to remember what he has done, so Alhaitham offers to go to the House of Daena to look into his past. Follow Alhaitham to the House of Daena.
Ride the elevator in the middle of the House of Daena to reach Alhaitham. Talk to him.
Investigate the three books laid out on the desk in front of you while waiting for Alhaitham to conclude his research. After reading all three books, the quest will progress. You and Alhaitham will learn Ilyas was hailed as an “academic hero” after reporting academic fraud to the Akademiya. However, this does not bring Ilyas any peace. After Ilyas collects his pay, you decide to accompany him on a trip to Gandharva Ville to learn more and deliver his paycheck to his sister.
After meeting with Ilyas’ sister, the quest will conclude. Your next goal is to stop Siraj before he completes his experiment. Completing the quest will reward you with 550 Adventure EXP, x38,100 Mora, x4 Hero’s Wit, and x8 Mystic Enhancement Ores.
