The File X in Spy Island consist of a file that has an information about the head of the B.A.D organization. If you slide the paper back into the file so that only first row of letters can be seen. You can now read a secret message from top to bottom that says: DON’T TRUST DIRECTOR D.
How to get the File X
Outside the restaurant of B.A.D. Bistro, run right until you see a guy in the bushes wearing camouflage. Talk to him and he’ll give you a folder called File X.