Left 4 Dead/The Greenhouse

Your team starts off in a greenhouse, and sees an airplane fly overhead. To win, you need to reach the airport for the evacuation.

Route

 * Forward to the greenhouse - climb the ash pile for free shots on enemies.
 * Go through the window, it's slightly faster.
 * Turn right and cross the roof-ramp to the next building.
 * Enter the window, and go forward a few rooms.
 * Exit via window, and climb the ladder to enter another building by it's window.
 * Climb out onto the truck.
 * Watch the car alarm.
 * Beeline into the hotel and into the saferoom.