It's 100 miles from Dallas to the little cross roads in East Texas where the brick plant sits. That gave us plenty of time to talk.

Mike explained that he'd already checked, as slyly as he could, on whether there was any record or indication of illegal dumping at the site. The brick plant and quarry had been there 60 years, built right after World War II when the home building boom in Dallas demanded ever-increasing brick production. Nearby gas wells provided the fuel to fire the high quality clay found adjacent to an intrusive quartz "dike" formation that rose to the surface in this location--hence the name "Stonewall."

The operation is stable, continuous and conservative, he said. The company is the largest employer in the community.

"I don't think this is your standard case of CYA," Mike said as we sped out of the searing city. "I think they really are worried they've struck something dangerous. The illnesses started when they opened up a new section of the clay pit."

I was jotting down some ideas and notes on a pad on my knee as we crossed into Kaufman County. "Have you thought about some biological contaminant, something that may have been uncovered in the clay, dried out and blown around?"

"Yes, and no, that clay is sterile."

I must have looked surprised, because Mike looked over. "Yep, I thought that was strange, too, like the dog that didn't bark in the Sherlock Holmes story."

"Silver Blaze."

"What?" Mike turned his head again.

"The Mystery of Silver Blaze. Holmes knew the horse napping was an inside job because the watchdog didn't bark. Sterile, huh?"

"Yep. Couldn't even raise a culture."

"How did you get a sample back to Dallas so quick? And where did you keep a culture? Like you know biology."

"Please, don't underestimate me. It was a hunch, but I was right."

I was scratching the back of my head. "Dammit, I understand the clay being sterile after it leaves the kiln--but before?"

"Makes you think of radiation sterilization, doesn't it?"

"Yes, but that's impossible, you won't even find that in uranium deposits--I think."

"We may be in over our heads," Mike said as he stared straight ahead down the highway, I hunched back in the seat. "Onward through the fog."

Mike smiled as we crossed into Henderson County.

It was obvious when we came to Pineville, the small town that was the big plant's home, because almost all the houses and buildings we passed were of the same red brick. The plant wasn't very hard to find. A towering brick chimney loomed like a rocket over the Pinrey Woods.

The plant manager, Rudy Gerfertig, knew we were coming thanks to an extended phone call from Mike along the way. He knew Mike was the overall project director, and he was told I was an environmental engineer.

The headquarters looked out of place, dwarfed by towers, conveyor belts and looming piles of clay and sand. Gerfertig was a small man with blond hair; Mike loomed over him as he shook his hand and introduced me.

"It's good to meet you, too, Mr. Koster. I'm glad things are moving along." He seemed almost too polite, perhaps self-conscious. "Do you prefer John or Jack?"

"Call me John; I prefer John. Something about the way 'Jack Koster' trips off the tongue invites trouble."

Gerfertig gave a little laugh while Mike rolled his eyes. I nudged him as we walked down the hallway to the back door, "Hey, I really don't like being called Jack."

We hopped into Gerfertig's bright red Ford 350 diesel and drove the mile or so to the clay pit. Two or three trucks were scattered around as bulldozers and backhoes scraped and hoisted the dark red clay.

Gerfertig pointed to the area farthest from us, right up against and below a low, long cliff. "That's the dike, the stonewall," he said. "After all these years, we finally started digging right up against it, and that's the place where we had the problems.

"Last week, when the men went to the hospital, I stopped operations." Gerfertig explained. "We haven't been back since."

"Has our team been there yet?" I asked Mike.

"They are still in the plant, they haven't worked their way out here," he said. "We're fixin' to leapfrog them."

Gerfertig seemed unhappy. "Even though there are only three sick men, that's three too many. I hope you understand. We've never had an illness cluster in the history of the company, now three men at one time."

"It's obvious you care about your employees," I said. "You're probably like a big family here."

Mike saw how I was looking over the landscape and asked Gerfertig if we could drive towards the cliff. After a while, as I walked around the area, I noticed a spot where the clay seemed to be darker and denser, almost crumbly. I waved towards Mike and the manager and they walked over.

I poked at the spot with a branch that had fallen from the nearby cliff. "Anything different about this spot right here?" I asked Gerfertig. I was poking with a stick and grasping at straws at the same time.

I have no idea what I expected him to say--"Well, that's where we found the petrified buffalo crap," maybe. He took a gulp and after a little hesitation, said, "I guess that's caused by the mercury."