The fax from Sanford Rieff at Cheviot Labs was waiting for me, as he’d promised. He’d looked at the little froggy soap dish from its bulging eyes to its stubby feet. It had been made in China, surprise, out of a pewter alloy whose rough surface didn’t hold fingerprints well. Underneath the smoke stains, Sanford could still detect oil from human fingers; perhaps it would be possible to get a DNA sample, although he wasn’t optimistic.

The soap dish part of the frog was the back, which was hollowed out and had a hole in it for drainage. Someone had put a rubber plug in the hole and then poured nitric acid into the dish. The acid had burned out the plug, but traces of it remained, melted into the sides of the drainage hole.

“Nitric acid dissolves soap,” Sanford concluded, “so there was no soap residue in the bowl of the dish, but I took some samples from the sides; whoever used it for its intended purpose used a heavy-scented rose soap, probably Adorée, a cheap brand sold in most drugstore chains and discount stores. I have the frog secure in a specimen box. Let me know if you want it returned or if we should store it until it’s needed as evidence.”

I stared at the fax, willing it to mean something more than it did. What was it doing at Fly the Flag. Why did it have nitric acid in it? Maybe acid was used somehow in the manufacture of flags. Maybe they dissolved glue with it, or something, and tried to use the froggy as a container, but the acid burned out the rubber plug.

My precious clue didn’t seem to mean much, but I still went to my desk and typed up labels for a set of files: Fly the Flag, Arson, By-Smart, Billy, and put Rieff’s lab report in the Fly the Flag folder. That was productive. Standing at my worktable, I shut my eyes, trying to visualize the back of the plant, where the fire had started. I’d been inside only twice, very briefly both times. The mechanicals were down there, the drying room, the storage area for fabrics. I made a rough sketch; I couldn’t remember enough detail, but I was pretty sure the heart of the fire was in the drying room, not the fabric storage area.