Place the medallion in the beam of light to investigate inside the Sainte-Chapelle.
Assassin’s Creed: Unity guide – Sequence 2 Memory 2: Rebirth – Investigate Sainte-Chapelle
There are no optional challenges in this mission, which is the last before Arno becomes a proper, capital-A Assassin. Enjoy!
Investigate Inside the Sainte-Chapelle
Your goal here is above you. The easiest way to reach it is to go straight up the front wall of the building so you can go inside, then immediately turn 180 degrees, facing the way you came in, and climb up to the balcony. All you have to do is press the interact button at the beam of light to trigger a cutscene.
Here’s a bit of fun: crossing the Sainte-Chapelle to reach the new objective marker. Hop between the chandeliers then use the rope to reach the far side, where you’ll need to perform a leap of faith (swan dive) into the hole in the floor.
It’s time to follow Bellec again, but this time he doesn’t need you to guard him from anything, so just wander along behind him until you see a cutscene. Once that’s complete you’ll have to run an obstacle course, perform another leap of faith, and cross a floor which is breaking apart. No biggie.
Things get much harder in the next segment. You have to slide down a slope without hitting fire pits; the best way to do it is to follow the tutorial prompts to slow your slide as much as possible. Carefully pick your way down to the segment of broken floor on the right side of the map.
The rest of the obstacle course isn’t tough, but it’s easy to fail the next checkpoint if you’re not careful. What you need to do is move through the crowd and use eagle vision to locate your target without letting him spot you. One good approach is to use the left hand side of the crowd; you ought to be able to get behind your target and stealth kill him.