Answer:
You have to add the cards of the books and card packs. Card combos unlock clues. Complete the missions to unlock more clues. When you have all the card combos complete and you have played all missions you will have all the 39 clues. Don't use the replicator cards if not necessary. Use them when you need to unlock a card when it has not been unlocked even after you have added all the cards of the books and card packs. My agent card code is P2FHHNDHXP