We step over a pile of trash, fast food wrappers, and an old pillow long since abandoned. An earthy hostel for the homeless. Angela surmised as much in her research paper, and now I can confirm. Yay. Walking along the creased sewer trough becomes a lesson in endurance and balance as the minutes drag on. Thank God the tunnel is empty, and it doesn’t seem to have been used in ages. I wrap my arms around my chest for warmth, for comfort. Chang passes through a left turn but stops short in the doorway. “What is it?” I ask, joining her.

Skulls form a thick cross in a domed alcove. Dozens of them. A downward chute lies beneath the cross, a mouth of black the circumference of a human body. My hand flies to my chest, clutching at my heart, as the mental endurance I’d gathered threatens to crumble. “Are we going down there?” I point with the pocket flashlight, throwing shadow monsters around the hub.

Chang clears her throat. “Not here. The old sewer will lead us lower first to get under the river.”

Lower. Of course. I nod, then follow her to the right of the two paths. The skull arrangements become more frequent as the concrete gives way to dirt and puddles. Chang barrels ahead, undeterred. I focus on tranquil thoughts, mantras, meditations. This is not the hope chest Angela locked me in. This is a tunnel matrix with dozens of exits.

This is the burial ground of six million Parisian unknowns.

Pools of water become more common as the ground dips more steeply. I try not to think about where I am and what I’m doing, because when I do my throat closes. Deep breath, through the nose. A drop of water hits my forehead. “Are we close to the river yet?”

“We’re under it now.” Chang’s voice booms from farther ahead. The temperature is even cooler here, and my long sleeves feel nonexistent. Plink plink plink. A rock skitters behind me. I whirl, but the flashlight reveals the same pile of dirt I just passed. My mother’s gentle reprimand comes to mind: Pick up your feet, Shayna. I jog to fall in line behind Chang. A metallic taste expands on my tongue as my teeth catch a dry section of skin—a reminder that I’m alive. Sane. Alive.

“What do you do back home, Shayna?” Chang picks her way along a jagged section. Large hunks of earth and stone block the path, and she offers a hand to help me across—a sight I would find comedic (tiny Chang, adult-size Shayna) if I wasn’t so grateful she offered.

“Well, I start medical school Monday,” I grunt.

“Wow. That’s great. I know we’ve just met, but that seems like a good fit—or you could be a judge? Have you ever thought about deejaying?”

“Not really, no. Would you—?”