I was at the back of the plant, at the concrete platform where the barge had been tied the last time I’d visited the place. Tonight the steel doors surrounding the loading bay were rolled shut and padlocked. Two spotlights at the corners of the building cut the haze around me. As nearly as I could tell no one was anticipating a river approach.

I slid my gun hand over the top of the bank and kept the Smith & Wesson in front of me as I hoisted myself onto land. I rolled over and lay still for a count of sixty. That was Ms. Chigwell’s signal to start the climb herself. I could just make out the change in the darkness as her head popped over the edge of the bank—anyone farther away wouldn’t be able to see her. She waited another count of twenty, then joined me on the loading platform.

The steel doors lay in a shadow cast by the projecting roof. We moved close to them, trying not to touch them—the sound of arms or gun brushing on steel would vibrate like a reggae band in the still night.

In front of us the spotlights turned the fog into a heavy curtain. Using its draperies as a shield, we moved slowly around to the north end of the plant where the clay-banked lagoons lay. Ms. Chigwell moved with the practiced silence of a lifelong second-story woman.

As soon as we rounded the corner we moved into thicker fog and danker smells. No lights shone on the lagoons. We sensed their pungent presence to our right but didn’t dare use the flash. Ms. Chigwell stayed close to me, holding my muffler, feeling her way cat-footed behind me in the dark. After an eternity of careful steps, moving slowly through ruts, sidestepping metal scraps, we reached the front end of the plant.

The fog was thinner here. We crouched behind some steel drums and peered cautiously around them. A single light burned at the gate leading into the yard. After looking for a long moment I could make out a man standing near the entrance. A sentry or lookout. An ambulance was in the center of the drive. I wished I knew if Louisa was still in it.

“Is she going to show up or not?”

The unexpected voice near my left startled me so much, I almost knocked myself against the steel drum. I recovered, trembling, trying to control my breathing. Next to me, Ms. Chigwell remained as impassive as ever.

“It’s been a little over two hours. We’ll give her until one. Then we’ll have to decide what to do with the Djiak woman.” The second voice belonged to my anonymous phone caller.

“She’ll have to go into the lagoon. We can’t afford any more traces.”

Now that my heart had settled to a less tumultuous pace, I recognized the first speaker. Art Jurshak, showing a strong family feeling for his niece.

“You can’t.” The second man spoke with his usual uninterested coldness. “The woman’s going to die soon anyway. We’ll just get the doctor to give her a little shot and return her to her bed. Her daughter will find she died in the night.”