Before you start the fourth chapter of the inFamous Paper Trail, make sure that you have completed all of the activities of chapter three. What is meant here is the ninth optional mission and the clues connected with it, on the http://infamouspapertrail.com/ page. On the map, find the new yellow marker and head towards it.
The starting point of the fourth chapter, connected with the inFamous Paper Trail, is in the street, in the North-Eastern part of the Market District. Approach the marker and, after you log on to the page of the inFamous Paper Trail Project, confirm that you want to continue.
As usually, you will have to chase Celia, i.e. the paper bunny. Just like in the previous chapters, it is impossible for you to lose the chase, because Celia will be stopping, on a regular basis and allow you to catch up. During the chase, use the Neon, or the Video powers, thanks to which you will not have any problems reaching the rooftops. The chase ends next to the structure shown in the above screenshot, in the Seattle Centre. You need to reach the top of the structure and, the easiest way to do that, is by using the Neon power (run up one of the props) or with Video (catapult from one of the nearby satellites).
Regardless of how you reached the top of the structure, you need to collect the Origami Dove there. You only need to reach the place, from which you send the gathered evidence and it is located to the North-East of here.