Six boys and a camel, and the boys were cheaper to replace. Some were orphans and escaped slaves, but most were off casts — teenagers abandoned by families too poor to keep them. When Shahib offered him the work, Jaheje hadn’t eaten in days.

Only the desperate would try crossing the Sai Kahleek, but those with any meager possessions bartered for Shahib. Jaheje looked across the cooking fire at the older boy. A few small tufts of facial hair had sprouted on Shahib’s cheeks, and his voice no longer cracked when he spoke. Few boys survived crossing the desert for more than a couple seasons. No one chose to do it after earning any money. No one except Shahib, who had walked the Sai Kahleek for almost ten years.

Shahib whistled and the other boys ran to his side. He showed them how to cut the callouses from their feet.

“Feel each step,” he instructed. “Start with your big toe, then roll outward until your whole foot touches down. Only then do you shift your weight from your rear foot.” He stood and demonstrated how to move with long, silent strides.

“Practice,” he explained. “If the camel walks too slowly, it will reveal our presence. You must be quiet, and you must be swift.”

Jaheje’s feet bled badly the first day; he nearly fainted from the pain. He practiced long after the caravan stopped and the ground cooled. By the fourth day, the pain was so intense, he used a bit of leather to bite down on. Shahib complimented him on his technique.

Shahib laughed as he indicated it to the other boys. “Watch,” he said. “Jaheje is quieter than me. Copy how he moves. Each step as soft as a mouse, each stride as long as a gazelle. Yes, this is how you survive Sai Kahleek.”

Longing as much for the older boy’s praise as the training he needed to survive, Jaheje soon followed him everywhere. He saw how Shahib rested with one foot raised and wrapped around the pendant spear. He saw how Shahib retied the spear’s pendant every morning, making sure the flag’s cut-cloth always flowed like the leaves of a desert palm. He saw how Shahib’s eyes searched the desert in a pattern, over and over, stopping only when he closed them for sleep.

After the second moon, they arrived. From the top of the dunes, Jaheje looked down at the skeleton of the dead god. No one knew what the monster had been when alive, but its huge ribs raked into the sky, each casting a shadow that engulfed the caravan as they passed. Its bones meant they were entering the Sai Kahleek.

Northerners called Sai Kahleek the “Bone Sea,” but this was a mistranslation. The Laaji tribes had never seen an ocean. Sai was the word the Laaji used for plains of sand and loosely packed rock, which were slow and painful to walk on. It meant the land was pockmarked with tunnels. It meant the Xer’Sai preyed here. It meant death lurked beneath the sand.

Dragging the old camel behind them, the team of boys left before dawn, a half day’s march ahead of the caravan.

Jaheje found his first burrow on the second day, and waved his signal flag. Shahib soft-stepped over to him. They approached the burrow cautiously and stopped a dozen yards from it. Its opening was no larger than a melon, but from it, the poisonous vapors of activity brewed. Shahib sent one of the boys back to redirect the caravan.

Jaheje looked back and asked Shahib, “Can we kill a Xer’Sai that large?”

Shahib scratched his chin, responding, “Their skin gets harder with age.” Slowly, a grin appeared proudly. “Last season I killed one the size of a jackal. We lost the camel, but I killed it.”

Jaheje smiled, enjoying his mentor’s boast. But he found himself asking, “Does Rek’Sai exist?”

Shahib chilled, his mood suddenly bitter. “I have seen her.” But before Jaheje could ask about the famous beast, Shahib stood and told Jaheje to keep moving. They crept away from the burrow, listening, waiting, scanning the horizon for any movement.

When Jaheje heard the first gong of a sounding bell, it took him a moment to process what it meant. Something was coming from behind them, to the east. He had been so focused on looking for hidden burrows, he had forgotten to watch the horizon.

The camel brayed, and Jaheje looked for the signal spears of the other boys in his crew. At the edge of his visibility, he could see their three flags.

The bell sounded again. The boy who had sighted the Xer’Sai would now use the sounding bell to confuse the beast. Jaheje had to chase the camel away from the path of the caravan and toward the lookout. Assuming the lookout wasn’t killed, the Xer’Sai would follow the camel away from the caravan and allow the lookout a safe path to retreat.

Jaheje could see Shahib running toward him. The bone-thin teen had abandoned silent-stepping, racing as fast as he could toward the camel and Jaheje. Shahib dropped his spear as a cloud of dust suddenly appeared behind him.

Jaheje ran to the huge king-bell attached to the camel. He dragged it down to the ground and struck it with all of his might. Even muffled by the earth, the sound battered his ears. He kept hitting, but the cloud of dust pursuing Shahib didn’t change course. Each second it gained ground.

At the moment, it seemed certain to overtake Shahib. Instead of running or dodging, he froze and screamed, “Don’t move!”

The other boys stood as motionless as their bodies would allow. At the exact instant, the old camel began running.

And then, before a word could be spoken, an energy crackle hit them like a wall. The hair on Jaheje’s neck stood on end.

“It’s close,” Jaheje whispered.

“No,” Shahib warned. “It’s not close. It’s big.” And for the first time Jaheje saw real fear on the older boy’s face.

Shahib scanned the desert, looking for a fin, a dust cloud, anything. Then he judged the distance. “The caravan’s too far. If it heads for the camel we can make it to the rocks.”

Jaheje desperately turned, looking for the hidden creature. “Where is it?!”

In the distance, they heard the camel bray in pain. The animal’s screams ended suddenly.

“What could kill a camel that quickly?” Jaheje asked.

Shahib pushed them forward. “We have to reach the rocks,” he insisted.

And with that, they began to run.

When Shahib told them to stop, they stopped. When he indicated for them to silent-step, they did so. Jaheje could only hope Shahib saw what he did not.

But the black rocks seemed to run away from them. No matter how many steps they took, they never grew closer. So they ran as clouds covered the sun and the desert became black. They ran as the wind swept away their trail. They ran knowing the Xer’Sai was behind them; knowing it heard every misstep, every stumble. They ran knowing that it followed, and that every mistake led it closer.

When Jaheje saw it, it seemed to be a giant mouth cut into the rock, vapors hissing from it menacingly. The burrow’s entrance was so large, even standing upright, he would be able to walk into it without lowering his head.

“Rek’Sai,” he whispered in terrified awe. As he turned, he realized that all around them, the black stone was pockmarked with the creature’s giant tunnels.

Young Xalee gave voice to the horrible realization that they all understood: “She can tunnel through rock.” The cliffs they had thought to be their salvation were instead Rek’Sai’s lair.

“We should go back, try and reach the caravan,” Xalee suggested.

“Try if you like,” Shahib answered.

“We can silent-step.”

“A day’s travel,” Shahib cautioned. “Can you travel soundlessly for a whole day?”

“What will you do Shahib?” Jaheje asked.

“If we go back, we will die in the Sai Kahleek. I will go forward and pray a guardian watches over me.”

Xalee asked, “Where does this valley lead?”

“It doesn’t matter where it leads. It is our only choice.”

They moved cautiously along the cliffs, entering a wind cut valley, and hoping it would lead to water soon. Avoiding the monstrous burrows was impossible. Each boy silently prayed Rek’Sai had heard, and pursued, the distant caravan instead of them.

As the sunlight crept over the edge of the valley, it revealed the desolate obstacle they faced. It was impossible to walk silently in the canyon, for bones were scattered underfoot. The sound of each footstep echoed with a hollow lifelessness.

She launched from an unseen hole behind them, which had appeared dead. For Jaheje, everything became a blur.

“Back!” Shahib screamed to the others. “Get downwind!”

The warning was already too late for Xalee. The creature brought down the boy like a wolf taking a mouse. Her huge fangs snapped Xalee’s spine, killing him before he could cry out.

Rek’Sai loomed above Jaheje, twice his height. Her powerful forelimbs stalked left and right. Her leech-like tail, many times the size of an alligator, dragged behind her body. Her long tongue rose, then swayed like a dancing cobra, sniffing the wind.

Jaheje could feel every muscle in his body aching to move. He stood transfixed as the huge Xer’Sai turned toward him. Gore covered the beast’s eyeless face and armored beak.

Rek’Sai was so alien and perfect in her deadliness, Jaheje felt his mouth open in awe. The boy gripped his spear staff, certain he wouldn’t be able to pierce her armored hide if she attacked.

“Down!” Shahib barked.

All the boys ducked flat to the earth as Rek’Sai’s “fin” pulsed a sickly green color. Jaheje could feel the invisible energy crackling above him.

The Xer’Sai turned, facing the distant caravan. Her tongue sniffed the air again, and considered the distance. Suddenly, the fin returned to its original violet color, and Rek’Sai pulled Xalee’s body down into her burrow.

Save the pool of thickening blood and Xalee’s absence, no evidence of the great beast remained.

Shahib whispered to go. The survivors silently retreated, deeper into the canyon.

No one spoke. The dark stone, pockmarked with burrows, robbed them of the ability to speak, to cry, to mourn.

Breaking free of the spell, his exhaustion cast over him. Jaheje looked around the canyon walls. He realized in an instant the enormity of what stalked them and why Shahib had decided to press on. Since Omah ‘Azir’s time, when stone was clay and Shurima built itself to the sun, Rek’Sai had fed here. This valley was hers alone. And all believed the Xer’Sai existed only to eat.

“But why do they stay here?” Jaheje said aloud.

Suddenly, the monster appeared. She burst out of the ground in front of them, diving at Jaheje.

Jaheje ducked as Rek’Sai soared past him, her mass blocking the sun. As she landed, her forelimbs ripped apart the ground and she disappeared beneath the surface.

Hidden in the brush, VezKah, the youngest boy, motioned Jaheje closer. Just then, his mouth opened in horror. A pulse of dark energy ripped from Rek’Sai’s fin, tearing apart the earth as she rushed toward VezKah. The earth cracked apart as Rek’Sai ripped the ground up and threw the boy into the air. VezKah landed in a heap as the huge fin rushed toward them.

Together, Shahib and Jaheje ran out of the gully as quickly as they could.

The creature lurched forward, then slowed a rhythm, which matched the swerving pattern of her pursuit. She pushed them even further into the valley, blocking any other road of escape.

Silent-stepping was meaningless now. Rek’Sai was too close. All that was left was to run.

When Caleeb lost his breath, Rek’Sai took him. Seeing this, Shahib stopped. He collected Caleeb’s spear and waited. All around him, the air churned and bent like a reflection in the water.

“What are you doing?” Jaheje whispered.

“I will be the camel. Go silently.” Shahib acknowledged the walls around them. “Tell people what you have seen here.”

Jaheje followed Shahib’s eyeline. Behind him, the stone cliffs had been cut apart by burrows into a pattern of intersecting circles. From them, a bizarre connection of ink-black energy flowed and dripped like a sticky liquid. And through this matrix, an incompressible reality bent and twisted as someplace else prepared itself to enter our world.

Hidden in this isolated valley, the true lair of Xer’Sai was a half-constructed tunnel. A tunnel to the nightmare place where these creatures had been born, and fouler things waited hungrily at this unfinished gateway to our world.

“Keep going, Jaheje,” Shahib said with a tired smile. “Each step as soft as a mouse, each stride as long as a gazelle. You must survive the Sai Kahleek.”

Jaheje made it to the far cliff before he heard the scream. Turning to look, Jaheje rolled his foot down, then slid his heel to the ground just as Shahib had taught him.

He did this as his teacher was reduced to the sound of bones snapping, and the great beast chewing.

Jaheje watched as Rek’Sai opened her maw and pulled a sticky ball of dark energy from Shahib’s ruined body. The ball rotated as tendrils dripped to the ground, sticking and stretching as Rek’Sai manipulated it into a pattern, which she attached between two of the burrows.

Jaheje looked away, then turned silently and soft-stepped out of the valley.

Jaheje ran out of sweat the next day. He felt his dry eyes scratching against his eyelids. His lips swelled, then split open bloodlessly.

When his calf muscles locked in a cramp from dehydration, and he was no longer able to soft-step, only then did he fall to the ground to cry. He cried for the days of hunger he’d suffered before joining Shahib’s caravan. He cried for knowing his parents off cast him instead of his brothers. He cried for Shahib, the first person who’d shown him kindness. And it was those last tears that dragged him back onto his cramped legs and made him stand. Knowing each shaky and tired step revealed his position to any Xer’Sai nearby, Jaheje stumbled onward.

When Jaheje reached the great river Renek and told his story, few believed him. But soon, those who tried to cross the Sai Kahleek with any meager possessions left, bartered for Jaheje. And Jaheje taught off cast boys how to cut the callouses from their feet and how to soft-step by rolling their heel. He taught them how to survive the Sai Kahleek, and he warned his students of the monster named Rek’Sai.