Captain Sidekick Trophy in A Plague Tale: Innocence
Stay with the captain
How to unlock Captain Sidekick~If missed, can be obtained via chapter select~
Chapter 14: Blood Ties
Definitely the hardest trophy. In this chapter, you will be in control of Hugo. Once you reach a cutscene with Grand Inquisitor Vitalis, the Archbishop and Captain Nicholas you're close to start this trophy (It’s about half way into the chapter). After the cutscene ends, the objective is to follow the captain as he makes his way to the dungeon. At one point you will get cut off after you go through the courtyard and he will lock a door. You need to be inside this room first for the trophy to pop. Follow the captain and stay closely behind him, you'll get to a courtyard and Hugo will say 'I can see the sky'. The captain will go right, and stop for a moment to talk to one of the guards. The door entrance you need is at the opposite end of the courtyard so keep moving and progress using the left side. Go underneath the hallway and sneak past the guard outside at the end to stay ahead of the captain. Once you are out of the courtyard and through the door do not go left up the stairs, instead sneak forward through the door that Nicholas will go through and lock (just keep going straight). After you go through the door, hide underneath the wooden table on the right side of the hallway. Sit and wait for the captain to catch up to you. Once he is through the door and closes it, the trophy will pop.
Video Guide: LINK
Credit to NonstopTrophies