Take PORTAL COMBINATION 1/3 (A).
Remove the poster (green); take the MAILBOX CLUE (purple).
Put down the MAILBOX CLUE (B); enter the correct code (C) and take the KEY (D).
Insert the KEY into the lock (E); turn the key.
Take the note (F).
Open the book; take PUZZLE PIECE 1/2 (G).
Play the HOP.
You receive the artifact (H).