1. Mark of the Sniper takes place in the Entrance Plaza.
2. This opening cutscene initiates once you enter the plaza. A dad and his two son's are having a family outing, sniper-style.
3. You've got several options here, all of which are good. You can snipe these three from afar, rush them with melee weapons, or chase them down with the shotgun (my preference).
4. The melee and shotgun options are especially advised if you're of a level where your running speed allows you to easily catch up.
5. Once all three snipers are down, talk to Wayne in the far right corner of Estelle's Fine-lady Cosmetics and get him to join.
6. Descend the escalator and clear a path to Gramma's Kids, the locale for the next scoop mission, The Woman Who Didn't Make It.
7. Speak with Jolie and learn that she's upset over her friend Rachel. You may need to leave the store to get Jolie to join you once her dialogue options are exhausted.
8. With Jolie and Wayne in tow, lead them safely up the nearby escalator.
9. Your destination is Rachel's current location - Ladies' Space.
10. Turn right at the top of the escalator and find Ladies' Space a short distance on the left.
11. Ready your camera to snap Jolie's and Rachel's dramatic reunion.
12. Directly across the hall is Ned's Nicknackery, the locale for the Antique Lover scoop.
13. Step inside and repeatedly speak with Floyd to convince him to join your troop.
14. Before leaving, be sure to check out this Battle Axe. One of the most powerful weapons in the game, it will let you clear out an elevator in record time.
15. You've now got four survivors to escort back to the Security Office, and Floyd will travel a lot faster if you carry him. Lead everyone back down the escalator.
16. Drop off Floyd at the Paradise Plaza entrance, just behind the escalators. Set a Waypoint to the same location and clear a path for the rest.
17. It's then just a short distance to the Warehouse door.
18. 200,000 PP is your reward for rescuing all four.
19. Use the yellow door to view this cutscene revealing Dr. Barnaby's explanation of events.
20. If you rescued Ronald earlier in the Restaurant Man scoop, you'll have been given the "Ronald's Appetite" mission. Give him some food now to avoid a mutiny and earn 10,000 PP.