Kalila blinks at Garrek's words. He doesn't think the shadowed figure is one of the Vultures? But then...the Vultures sounded like a bunch of rogues. She wouldn't be surprised if stealth and subterfuge is part of their methods and they just hadn't been caught yet...

Before she could say anything to him, Miller clears his throat. She immediately turns to face him once more, her eyes darting between him and the hall behind him, to make sure the shadow wasn't coming out. She raises an eyebrow as he bites the gold coins to test them. When he asked his suspicions, she answers him, with eyes wide with surprise from the accusation. She answers him, "Miller, you give me too much credit when it comes to magic. I do not even know how to accomplish that! No, my business with you is genuine," 

She considered what to do next, and she decided that Garrek was right. She needed to tell him, and being direct is now a necessity at this point. She just needed to be careful that the shadow doesn't hear her.

She approaches closer to the counter, and she gestures him to move closer. She does glance to the back hall to see if the shadow comes out. She whispers to Miller, "I apologize for the confusion, but I was trying to tell you earlier: Someone is in your back room. You may be in danger if we leave you alone,"