Here are total strangers. People Tila would sketch in cafes and restaurants. I can remember when she drew the old man at the bar down the street—not that he looked that old (hardly anyone in San Francisco does), but you can still tell when someone’s over seventy. Something about their eyes.

This man was always there, at the same seat at the bar, with the same glass of SynthScotch, staring into the distance with the withdrawn look that meant he was accessing his ocular implant. We often used to wonder what he was reading or watching, lost in his own little world, not moving except to raise the glass to his lips or lift his finger for a refill. I remember how my twin looked, bent over the sketchbook as she shaded in his features, while I sat across from her sketching out calculations for whatever project I was working on. Companionable silence.

I close my eyes tight, not wanting to cry again. But I don’t have any tears left. I make my way through the rest of the house, looking under the sofa cushions, in every kitchen cupboard, all the various nooks and crannies.

In the middle of the kitchen, I stand up, my eyes wide. Why hadn’t I remembered?

I do know where Tila hides her secrets.

She showed it to me once, not long after she moved in. It was to be her version of the cookie jar, where I could leave her messages if I was passing by. Such a childish game, but I’d appreciated it. Yet in all the months she lived here, I never left her any messages. I kept meaning to, but never did. Hers were always so clever, so thoughtful, and when I tried to think up a return message, they all seemed unbearably dull. She never mentioned the lack of baubles and notes. I never knew if she was hurt by that or not.

I go to her spare bedroom, grunting as I pull back the bed. Another reason I didn’t leave messages: it’s harder to get to than a cookie jar in the kitchen. Tila was always the more paranoid of us, though, and now I understand why.

I can’t see any evidence that the police moved the bed, and the cubbyhole she built behind it seems untouched. I take the key she gave me from my purse and put it into the lock, and the door swings open.

Inside are another sketchbook and a datapod. The pod is only the size of my thumbnail. I want to bring it up on my implants right away, but I’m also afraid of what it may contain.

I open the sketchbook. The first few pages are blank, but near the end, the pages are filled.