Thunderhead

Working swiftly, Aragon donned a pair of plastic gloves, removed a scalpel from his kit, positioned it just below the last rib, and with a short movement opened the body. Reaching inside with a long narrow set of forceps, he twisted his hand sharply, then retracted it. On the end of the scalpel was a small bit of pink flesh that looked to Nora like lung tissue. Aragon dropped it inside a test tube already half filled with a clear liquid. Adding two drops from a separate vial, he stoppered the tube and swirled it around in his hands. Nora watched as the color of the solution turned a light blue.

Aragon nodded to himself, carefully placed the tube inside a styrofoam case, and repacked his instruments. Then, still kneeling, he turned toward Nora. One gloved hand lay, almost protectively, over the corpse’s chest.

“Do you know what killed him?” Nora asked.

“Without more precise tools, I can’t be a hundred percent sure,” Aragon replied slowly. “But one answer does seem to fit. All the crude tests I’ve been able to run verify it.”

There was a moment of silence. Smithback took a seat on a rock a cautious distance from the body.

Aragon glanced at the writer, then back to Nora. “Before I go into that, I need to tell you some things I’ve discovered about the ruin.”

“About the ruin?” Smithback asked. “What does that have to do with his death?”

“Everything. I believe the abandonment of Quivira—indeed, perhaps even the reason for its very existence—is intimately connected with Holroyd’s death.” He wiped his face with the sleeve of his shirt. “No doubt you’ve noticed the cracks in the towers, the collapsed third-story rooms of the city.”

Nora nodded.

“And you must have noticed the great rockfall at the far end of the canyon. While you were off searching for the horse killers, I talked with Black about this. He told me that the damage to the city was done by a mild earthquake that struck around the same time the city was abandoned. ‘The dates are statistically equal,’ he said. The landslide, according to Black, also occurred at the same time, no doubt triggered by the earthquake.”

“So you think an earthquake killed all those people?” Nora asked.

“No, no. It was just a temblor. But that rockfall, and the collapse of some buildings, was enough to raise a large cloud of dust in the valley.”

“Very interesting,” Smithback said. “But what does a seven-century-old dustcloud have to do with Holroyd’s death?”

Aragon gave a wan smile. “A great deal, as it turns out. Because the dust within Quivira is riddled with Coccidioides immitis. It’s a microscopic fungal spore that lives in soil. It’s usually associated with very dry, often remote desert areas, so people don’t come into contact with it much. Which is a very good thing. It’s the cause of a deadly disease known as coccidioidomycosis. Or, as you might know it, valley fever.”

Nora frowned. “Valley fever?”

“Wait a minute,” Smithback interjected. “Wasn’t that the disease that killed a bunch of people in California?”

Aragon nodded. “Valley fever, or San Joaquin fever, named after a town in California. There was an earthquake in the desert near San Joaquin many years ago. That quake triggered a small landslide that raised a cloud of dust, which rolled over the town. Hundreds became ill and twenty died, infected with coccidioidomycosis. Scientists came to call this type of deadly dustcloud a ‘tectonic fungal cloud.’” He frowned. “Only the fungus here in Quivira is a far more virulent strain. In concentrated form, it kills in hours or days, not weeks. You see, to get sick you must inhale the spores—either through dust, or through . . . other means. Mere exposure to a sick person is not enough.”

He wiped his face again. “At first, Holroyd’s symptoms were baffling to me. They did not seem to be from any infectious agent I knew of. Certainly he died too quickly for any of the more likely suspects. And then I remembered that rust-colored powder from the royal burial.”

He looked at Nora. “I told you about my discoveries with the bones. But do you recall those two pots, full of reddish dust? You thought they might be a kind of red ochre. I never told you that the dust turned out to be dried, ground-up human flesh and bone.”

“Why didn’t you tell us?” Nora cried.

“Let’s just say you were preoccupied with other things. And I wanted to understand it myself before I dangled yet another mystery in front of you. In any case, while puzzling over Holroyd’s death, I remembered that reddish dust. And then I realized exactly what it was. It is a substance known to certain southwestern Indian tribes as ‘corpse powder.’”

Nora glanced at Smithback and saw her own horror reflected in his eyes.

“It’s used by witches to kill their intended victims,” Aragon continued. “Corpse powder is still known among some Indian groups today.”

“I know,” Nora whispered. She could almost see Beiyoodzin’s drawn face in the starlight, telling them of the wolfskin runners.

“When I examined this powder under the microscope, I found it absolutely packed with Coccidioides immitis. It is, quite literally, corpse powder that really kills.”

“And you think Holroyd was murdered with it?”

“Given the huge dose he must have received to die so quickly, I would say yes. Although his illness was surely made worse by constant exposure to dust. He did quite a lot of digging in the rear of the ruin in the days before his death. The fact is, we’ve all been exposed to it.”

“I did my share of digging,” Smithback said, his voice a little shaky. “How much longer before we get sick, too?”

“I don’t know. A lot depends on the health of our immune systems, and on the degree of exposure. I believe the fungus is much more concentrated in the rear of the city. But regardless, it’s vital that we get out of here and get treatment as soon as possible.”

“So there’s a cure?” Smithback asked.

“Yes. Ketoconazole, or in advanced cases where the fungus has invaded the central nervous system, amphotericin B injected directly into the cerebrospinal fluid. The ironic thing is, ampho is a common antibiotic. I almost brought some along.”

“How sure are you about this?” asked Nora.

“As sure I can be without more equipment. I’d need a better microscope to be absolutely sure, because in tissue the spherules are only about fifty microns in diameter. But nothing else explains the onset of symptoms: the cyanosis, dyspnea, the mucopurulent sputum . . . the sudden death. And the simple test I just performed on Peter’s lung tissue confirmed the presence of coccidioidin antibodies.” He sighed. “It’s only in the last day or so that I began putting this together. Late yesterday evening, I spent some time in the ruin, and found other examples of corpse powder stored in pots, as well as various odd types of tools. From this, and from all the trashed bones in the Crawlspace, it became quite clear that the inhabitants of Quivira were actually manufacturing corpse powder. As a result, the whole city is contaminated with it. The entire subsoil of the ruin is full of the spores, its density increasing toward the back. That puts the greatest concentration in the Crawlspace, and especially in the cavern of the Sun Kiva that Black discovered.”

He paused. “I told you my theory that this city was not really Anasazi after all. It was Aztecan in origin. These people brought human sacrifice and witchcraft to the Anasazi. It’s my belief that they are the marauders, the conquerors, who caused the collapse of Anasazi civilization and the abandonment of the Colorado Plateau. They are the mysterious enemies of the Anasazi that archaeologists have sought all these years. These enemies did not kill and exert control through open warfare, which is why we’ve never found the evidence of violence. Their means of conquest and control were more subtle. Witchcraft and the use of corpse powder. Which leaves little or no trace.”

His voice fell. “When I first analyzed that burial cyst Sloane uncovered, I felt it to be a result of cannibalism. The marks on the bones seemed to point to that. In fact, Black’s protests to the contrary, it was the obvious deduction to make: Anasazi cannibalism is currently a hot, if controversial, theory. But I no longer think cannibalism is at the bottom of all this. I now believe those marks on the bones tell an even more terrible tale.”

He looked at Nora with haunted eyes. “I believe the priests of the city were infecting prisoners or slaves with the disease, waiting for them to die, and then processing their bodies to make corpse powder. The trash from that