"Find Germain" is a mission objective in Sequence 12 / Memory 03: The Temple
Walkthrough[edit]
After that attack, Germain will disappear. You will need to find him again. Head to the other Northeast tower and slip downward. When you can, perform a Leap of Faith into the Hay Cart below. From there, head over to the Eastern courtyard. You can also head over to the East using the rooftops for some easy traversal.
In the Northern corner of the Eastern courtyard is the entry point you are looking for. It is guarded by 2 Extremists. Lob a Cherry Bomb past them to distract them. Use that to get inside.
Inside the catacomb go to the first intersection and turn to the right. Follow this corridor to the left. After that turn, free run over the gaps and follow the corridor to the main chamber. As you approach the door to it, Elise will catch up with you. She explains that she has not seen Germain leave. He is likely in the chamber in front of them. Go up to the highlighted door and interact with it. This will trigger a quick cutscene. Just be ready.