She pursed her lips and shook her head. "I feel for you, buddy. I haven't seen my boyfriend in months. He probably thinks I'm dead. Fortunes of war. We go back for your Ange, we're dead. If we push on, we have a chance. So long as we have a chance, she has a chance. Those kids aren't all going to Gitmo. They'll probably take a few hundred in for questioning and send the rest home."

We were moving up Market Street now, past the strip joints where the little encampments of bums and junkies sat, stinking like open toilets. Masha guided me to a little alcove in the shut door of one of the strip places. She stripped off her jacket and turned it inside out -- the lining was a muted stripe pattern, and with the jacket's seams reversed, it hung differently. She produced a wool hat from her pocket and pulled it over her hair, letting it form a jaunty, off-center peak. Then she took out some make-up remover wipes and went to work on her face and fingernails. In a minute, she was a different woman.

"Wardrobe change," she said. "Now you. Lose the shoes, lose the jacket, lose the hat." I could see her point. The cops would be looking very carefully at anyone who looked like they'd been a part of the VampMob. I ditched the hat entirely -- I'd never liked ball caps. Then I jammed the jacket into my pack and got out a long-sleeved tee with a picture of Rosa Luxembourg on it and pulled it over my black tee. I let Masha wipe my makeup off and clean my nails and a minute later, I was clean.

"Switch off your phone," she said. "You carrying any arphids?"

I had my student card, my ATM card, my Fast Pass. They all went into a silvered bag she held out, which I recognized as a radio-proof Faraday pouch. But as she put them in her pocket, I realized I'd just turned my ID over to her. If she was on the other side...

The magnitude of what had just happened began to sink in. In my mind, I'd pictured having Ange with me at this point. Ange would make it two against one. Ange would help me see if there was something amiss. If Masha wasn't all she said she was.

"Put these pebbles in your shoes before you put them on --"

"It's OK. I sprained my foot. No gait recognition program will spot me now."

She nodded once, one pro to another, and slung her pack. I picked up mine and we moved. The total time for the changeover was less than a minute. We looked and walked like two different people.

She looked at her watch and shook her head. "Come on," she said. "We have to make our rendezvous. Don't think of running, either. You've got two choices now. Me, or jail. They'll be analyzing the footage from that mob for days, but once they're done, every face in it will go in a database. Our departure will be noted. We are both wanted criminals now."