The biff puts two fingers into her mouth, and blows, whistling like Hammer 
has rarely heard. The sound is loud and shrill and slices through the alley, 
faintly echoing. A sputtery rumbling arises. Out beyond the end of the alley, 
over on the other side of the street, five cycles glide into view, coming to an 
easy halt. The riders wear black synthleather and at least one of them has a 
submachine gun slung from the shoulder.