The Whistler Whispered Back.

Darcy whistled back at the piping apparition. It tilted its head and stared at her for a few seconds. She explained that there was an evil dopple-ganger in their neighborhood, but she couldn't get rid of it. So here's the plan: You can scope out the neighborhood, then cut the doppleganger's head off or kick it back to dimension x or something. The figure didn't budge; darcy walked right past it with numinous terror.