A lucky thing: One of the first-floor cops is just opening the stairwell door, no doubt alerted by the symphony of alarm bells and buzzers that has begun to merge into a solid wall of hysterical sound. She blows by the guy; he puts one arm out in an attempt to stop her, sort of belts her across the waist in the process, throws her balance off, but this is a very forgiving skateboard, it's smart enough to slow down for her a little bit when her center of mass gets into the wrong place. Pretty soon it's back under her, she's banking radically through the elevator lobby, aiming dead center for the arch of the metal detector, through which the bright outdoor light of freedom is shining.