You need to Beat the 1st Puzzle perfectly as either the Explorer or Librarian.
Both players need to go and pick up the walkie-talkie, then the Explorer will see bloody writing on the wall.
Across from this writing there is a wall with 2 lit up coloured eyes, and below them a bunch of symbols.
Tell the Librarian the eye colours that you have, and the Librarian need to describe the symbols that they have in their library.
Once both are pressed successfully, the trophy will pop for both players!
Only press the 2 correct buttons, otherwise it won't count as a perfect completion.