As we walk down the stairwell, Cara tells us she needs to go to the basement. "Quick errand," she says. It's dark and quiet on that level, with a few emergency lights dimly illuminated along the bottom of the wall. Cara disappears behind a metal door, asking us to wait in the hallway for her. She's in there for a long time, and just when Leo starts to pace, she comes out holding two pairs of shoes.

"What took you so long?" Leo asks her.

"Not easy to find a pair his size," she notes, nodding in my direction. "Size 13, right?" she says to me.

"Good guess," I respond, raising my eyebrows at her. I look at the shoes, which are black, with chrome eyelets. "Where did you get these?"

She ignores my question. "These are what the prestigious Erudite wear - the leaders and teachers."

She turns to Tris. "Will a size six fit you?" she asks anxiously. "That's the smallest I could find."

"Close enough," Tris says, taking the blue canvas sneakers. "Thank you."

I look at the door Cara came through - the metal is heavy, and I can feel cold air emanating from behind it. Suddenly, I realize what's in that room, and where these shoes came from. I look at Cara in shock.

She won't meet my eyes and turns to go. No one says anything as we leave Erudite.

As we pick our way through the rubble and broken glass, Cara seeks me out. "I knew him," she says, still not looking at me. "It would bother him more that they might go to waste." I try and fail not to think about the fact that I'm walking in a dead man's shoes.

After a few minutes, I say to Cara, pitching my voice so no one else can hear me, "I was wearing shoes just like this in Tris's simulation."

Cara shoots me a look. "I see."

"Any idea how that's possible? Or how she knew when the Abnegation were first targeted?"

"What are you two talking about?" Tris asks from behind me. She was with Leo and Uriah, but she moves so quietly I didn't hear her, even over all the trash and debris and eerie, city-wide silence.

"You, of course," Cara answers quickly.

"What about me?"

"How you seem to know some things you shouldn't really know."

Tris is quiet.

"Any ideas?" I prod gently.

Tris shakes her head.

"Cara?" I ask. "I can tell you have a hypothesis." She smiles as I use her own words against her.

"I do," she confirms. "But I have to warn you that it's a SWAG."

"Is that some technical term?" I ask.

Cara laughs. "You might say that! It basically means I have not yet collected a preponderance of evidence."

We wait for her to continue as we move through the broken streets, because there's no point in trying to rush Cara. She finally sighs. "I think it has something to do with the purple serum," she says. "It may have a two-way transmitter."

"Two way?" I prompt her.

"Usually, Jeanine would put a transmitter in a serum so a computer could communicate with the person injected. But I think she made it possible for the person injected to communicate with the computer, too, and that's how she was recording the simulation."

She says nothing for several minutes. I clear my throat, "So?"

"So," she says slowly, "I think Tris used the two-way transmitter as a pathway into the Erudite mainframe while she was in the simulation."

Cara pauses again, letting us digest her theory. "I think maybe all those times it looked like she was sleeping, she was exploring."

"What do you think, Tris?" she says softly.

Tris is watching the ground, stepping carefully around broken pavement. "I don't remember," she responds, biting the inside of her cheek. "But if that's true, do you think it's something I can do again?"

"Absolutely not!" I say sharply, a little too loud.

"Shhh, Four!" Leo hisses. "We don't know who is out here!"

"Absolutely not," I repeat quietly. "We almost lost you – you were trapped inside your own mind. What if we can't get you out next time? No, no – there won't be a next time!" I'm so angry with her for even suggesting it, I can't look at her.

No one says anything for some time - we can see the Pire just ahead now.

Finally, I glance at Tris, from under my lashes. She's watching me, levelly, not saying anything. Cara is watching me, too. In fact they are all watching me, and I can feel their judgment hanging heavily in the air around us.

I take a deep breath. "Okay," I say. "Fine. You can all just shut up now."

"No one is saying a word, genius," Uriah comments.

"Yeah, you didn't have to," I say darkly.

It's going to be very annoying that I exposed my deepest secrets and fears to a roomful of people. But then again, maybe it's not all that bad – maybe the only way for me to get past my fears is to have help.

I'm startled when Tris slips her hand into mine. She's smiling at me. "It's not funny," I grump.

"No, but you're cute when you're angry. A little angry, anyway." She squeezes my hand and runs her finger along my palm. "Don't worry, Tobias. I am not going to do anything stupid, and I'm not going to do anything without talking it over with you." I squeeze her hand back and nod. That will have to be enough – I will have to learn not to ask for more than that.

Speaking of which... I clear my throat nervously as we work our way into one of the hidden entrance tunnels to Dauntless.

"Uh, Tris, do you want to just stay with me? Um, tonight, I mean?" I want her to move in with me, but I don't want to ask for too much, too soon.

"Yes," she says simply. "Of course." She leans against me, putting her arm around my waist as we stumble tiredly down the darks halls. I'm not sure if she means just tonight or always, but for now, I can let this be enough.