All: The thugs (and others) are now making no secret of their interest in your little group--they are practically stalking towards you, cudgels and daggers in their hands.
As you prepare to meet them, you suddenly feel paralyzed--unable to move anything except your eyes. And it's not just you--the entire crowd has stopped; frozen mid-step, eyes wide and darting from side to side. The babble of conversation is hushed; all you can hear is the soft drumming of the rain on the rooftops nearby and in the puddles at your feet. A wave of heat passes over you; the rain and puddles start to steam. You can't see much beyond the vague, nearly shapeless forms of those near you frozen in place in the thickening steam and mist.
You hear a sound--it sounds like a tinkling little girl's giggle, coming from nowhere in particular, yet clearly audible over the rain.
And then suddenly you can move again. The fog and steam quickly evaporates under the falling rain, disappearing in seconds. The crowd moves again as normal--although you remember clearly seeing their faces strained and wide-eyed throughout the event, with the exception of a few people (i.e., the six of you) everybody continues on about their evening as if nothing had happened. The thugs, and halfling, and others who were moving in threateningly are all gone--disappeared without a trace.