Remember, if you haven't used our clues pages yet, check out the instructions here to learn how they work and how to best utilize them. 

Card 4.jpg

Hint 1

You'll want to identify where these quotes came from first.

Hint 2

More specifically, you'll want to know the authors of these quotes.

Hint 3

The first names of the authors form an acrostic.

Solution

Final Answer: ISTANBUL

Card 4 B.jpg

Hint 1

Each string of numbers here represents a book.

Hint 2

These are all ISBN numbers.

Hint 3

Each title has the same number of letters as are in its ISBN number. The highlighted numbers correspond to letters in those titles.

Solution

Final Answer: "THEY ARE CALLED THE OUROBOROUS"

Card 4 C.jpg

Hint 1

This is an Arnold Cipher, but what is the key book?

Hint 2

This font seems familiar...

Hint 3

The quote from the front of the card that shares this font must be the key book for deciphering your Arnold Cipher!

Hint 4

There's a certain "art" to solving this one.

Solution

You'll need "The Art of War" to finish this puzzle.
You can access a free digital copy here:
http://classics.mit.edu/Tzu/artwar.html

The plaintext reads: "Carrying Military Intelligence From A Former General"

Card 4 D.jpg

Hint 1

These are some gorgeous book covers.

Hint 2

The authors will help you find their titles.

Hint 3

A secret message can be found using your titles.

Solution

Final Answer: PROTECT MY MOTHER