Story-related and unmissable. You’ll unlock this achievement after solving the seventh and final scenario in the game, triggering the ending story sequence.
To complete this sequence, you’ll need to take the following steps (please be aware, these provide an explicit solution to the scenario):
Upon returning to the mansion, travel back to the scene of Aurum and Thanos’ death. Climb the stairs here and you’ll now be able to pass through the double doors here. Follow the path through the following rooms and up another flight of stairs to find yourself back in the Chapel area, where Sixpence was murdered.
You’ll now need to return to the specific room in which Sixpence was murdered – this can be either before or after the murder, but you’re unlikely to arrive here before the murder without resetting time.
Walk up to the window behind Sixpence’s body and interact with it using Tequila’s mask’s power to shatter the window. Exit the room through the gap that it leaves behind.
A story sequence will now play out, setting out the final death for you to prevent. Once you regain control, continue to watch until the victim leaves the room for the second time.
Descend the ladder and interact with the bomb using your pocket watch, synchronizing with it.
Pick up the wire cutters in this room and interact with the bomb again using these.
...and you’re done! Enjoy as some of the game’s final secrets are revealed!
Credit goes to: https://www.xboxachievements.com/game/the-sexy-brutale/achie...