Without a disguise, you may experience problems trying to reach important items, characters, or rooms. This is reminiscent of Hokkaido from the previous season of Hitman. The Isle of Sgail contains a small amount of areas that you can visit without a disguise.Make sure to find these secret pathways during the exploration and remember the locations of important items (disguises, keys, keycards, etc.) secret pathway or use drain pipes that allow you to travel between the floors.
Thorough exploration is recommended, as it may enable you to discover e.g. The castle contains nine floors, each offering different rooms and kill locations.