Flight is the first chapter in Mirror's Edge.
After The Edge, Faith hears her sister, Kate, talking on her radio, reporting to another officer that she was going to Pope's office. After a while, (possibly) the same officer announced that shots were fired at Kate's location. Worried, Faith attempts to get to Pope's office building, with the help of Mercury and another Runner near the place.
Getting into Pope's office, Faith finds Kate and, of course, Pope... shot in the head. Kate explains that suddenly "everything went dark" and when she came to, someone had used her pistol to kill Pope. Merc warns Faith that Blues were nearing their position. Giving a scrap of paper from Pope's diary (and a hug) to Faith, Blues armed with Assault Rifles attack the Runner. As she escapes the building, a Helicopter follows Faith, firing at her until she gets into another building.
Getting nearly onto the ground floor, Merc tells Faith she must get fight though a plaza (filled with cops) and gain entrance into the tunnels to get to a outside railway. Doing so, and under heavy fire by Blues and the heli, she jumps onto a glass roof and crashes though, meeting up with a fellow Runner, Kreeg, who was planned by Merc to meet up with Faith. Both escape the scene.
While trying to get the achievement for speedrunning through this level, play through it a few times before attempting it. Make sure you know which jumps you don't have to skill roll on (there are a lot that you actually don't have to). Also make sure that you can run through the level in your head first. This means that you actually know the level and know what to do. You only have six minutes to do this level. If you don't know many alternate routes for this level, you could end up with a time of 5:59 if you do everything perfect, so make sure you can find alternate routes in practice before speedrunning. If no alternate routes are used, and you skillroll on every jump, you could end up with 6:05 or higher, so be sure to watch some videos first.