From where we were, I could see into the gallery, where another agent, a tall black man, walked past the gleaming onyx angel. That statue was big enough to hold Lena, but the base was solid stone.

There was another option. A room for staging installations, full of empty crates and bits and pieces of hardware, bases and supports and plenty of places to hide.

“The exhibition preparation room, just off the last gallery,” I said, pointing.

Agent Castillo spoke into her walkie-talkie and gestured to her counterpart. He nodded and called out to two police officers who’d just reached the top of the stairs. Together they entered the third gallery.

I edged closer, only to have them wave me back, but not before I could see the display inside. More mobiles with glass twisted into impossible shapes, smaller versions of the one hanging over the atrium, hung down from the ceiling or rested on invisible shelves. On two sides the walls were draped with black fabric, gathered and pleated until it appeared to flow like water, pooling onto the shelves and merging with the shadows, distorting a viewer’s depth perception. With the right lighting, the glass pieces would seem to move freely, their cords and metal wires invisible.

In the center of the room stood the biggest piece, a woman raised as if standing on a cliff, larger than life, three-dimensional and translucent, catching and refracting the light. When the agent strode past, the separate leaves of glass shivered apart on their metal strands and then came together again. Despite how light it looked, how easily it moved, I knew how deceptively heavy glass could be. The base looked like a sandstone cliff, rising from floor level to waist-high, the shimmering glass woman poised as if to leap.

She was still trembling, although no one was near.

The officers opened the door at the end of the room, shouting their identification before entering. But I didn’t hear a commotion or anything that sounded like an arrest. I could have sworn I felt Lena’s eyes on me, watching me.

I glanced up, but the red eye of the security cameras was still dark. The glass sculpture in the center of the room stilled, and the glass woman seemed to be looking right at me, challenging me. There was nowhere for Lena to hide in the first gallery or the second or in the base of this glass statue … then I knew.

Gently I touched Agent Castillo’s arm and pointed to the dark drape over the side wall. In the corner, where the fabric was bunched and gathered, a person with steely patience could hide, waiting for a quiet moment to slip away. The agent looked at me, and in her gaze, I felt myself weighed and judged. Complicit, stupid, attention seeking? No, the agent motioned for me to get behind her. She believed me, trusted me, and she drew her gun.