RIDDLE 1 - Air, sea, or land. It would be criminal not to use these wise guys, wouldn't it?
Find the Falcone Warehousing and Storage billboard (screen above) and scan it.
RIDDLE 2 - Can you find this cool couple before romance thaws?
The solution to this puzzle can be found inside Storage Warehouse 5B where you should head only after completing Heart of Ice. Use the previously inaccessible main door (screen above).
After getting inside the building, stand in front of the chamber with Nora Fries, beside which Mister Freeze should be (screen above). Scan them both. Notice! If Mister Freeze isn't here, make sure you've completed Heart of Ice in 100%, i.e. you reported to Freeze on the whereabouts of his wife.
RIDDLE 3 - Was this parasite ratted out, or does he continue to plague Gotham?
Find the Otis Flannegan Pest Control billboard (screen above) and scan it.
RIDDLE 4 - This question can only be answered from an unusual perspective. Can you get yourself there?
If you analyze the area in Detective Mode, you should note that there's an incomplete question mark there (screen above). In order to solve this riddle, you have to find the missing dot.
The dot in on the roof of one of the building east of the big question mark. The place was marked on the screen above. Remember to stand in such a place that the main part of the question mark and the dot create a whole.
RIDDLE 5 - Does Zsasz still pose a threat? This guy called to find out.
Find the body of an inmate leaned against a telephone booth (screen above) and scan it.
RIDDLE 6 - Which notorious family keeps talking trash?
Jump, swim or glide to the barque north of the Industrial District. Locate the name of the company it belongs to (screen above) and scan it.
RIDDLE 7 - Did you hear the HOLE story of how Black Mask escaped?
Find the Black Mask poster (screen above) and scan it.
RIDDLE 8 - Breaking news! Get out while you still can.
Find the closed hot-dog booth (Bill's Hotdogs) and examine its side. you need to scan the pages torn out of the Gotham City Globe newspaper (screen above).
RIDDLE 9 - If you're planning on making your mark in Arkham City, you'll need a special kind of realtor.
This riddle can be solved inside the building in which Zsasz's had his hideout. For more details regarding how to unblock and reach that location, check out the Cold Call Killer side mission walkthrough. Use the door leading inside the hideout (screen above).
After getting inside, head to the main room and scan the business cards on the table (screen above).