The 15th Street Sinners are a group of street kids who fiercely protect their territory against any semblance of authority - which usually boils down to police or the SLS, although they will fight a Triad member if they don't recognize them or think they can get away with it. Aside from their violent territorialism, their criminal activities usually involve vandalism, shoplifting, burglary, and occasionally charging 'tolls' to pass through their neighborhood; they prefer attacking unguarded targets or defensive confrontations on their own turf where they can control the situation.
The 15th Street Sinners have a base of operations at the 15th Street Mission, a large stone church with outbuilding and belltower on 15th Street. Their boss is named Freddy Z, and is apparently a foul-mouthed blonde woman with a hell of a right hook. There's also a repair shop called Ace Mechanics where Monkey (who apparently manages children connected to the gang) works. The priest that manages the mission is named Father Cameron.