Chapter 93

Mauna Loa, Hawai‘i

In Hawaiian, Mauna Loa means "Long Mountain," a fact Mac could not get out of his head as the lava continued to chase them down the trail.

It did not slow; it just kept coming.

They knew they risked falling if they ran too fast, but they had no choice; they had to stay ahead of the ropy pahoehoe lava or die. Some of it had begun to spill off the trail and down the fields of old lava from previous eruptions.

They ran harder, trying to ignore the thin air and the burning in their legs, spurred on by adrenaline and fear.

Mac thought it was too risky to move across the mountain and down the lava fields. He was unsure of the sturdiness of the open stretches, knowing that there were places on fields like this that could crack like eggshells and swallow them up, maybe into magma flowing below the surface.

There was no cell service, no way to call for help. He'd slowed long enough to check his phone with its dying battery. Cell towers were probably down all over the island.

Mac wondered what else on the island was down and where and how fast the rest of the lava was headed.

The observatory finally came into view, but it looked impossibly far away. Mac allowed himself a quick look back.

Shit.

As the trail got steeper, the lava came faster.

"We've got to get off the trail now!" Mac yelled at Rebecca. "We're going to have to risk cutting across the lava field."

"Is that safe?" she asked.

"As long as the quakes and tremors haven't weakened the old lava too much," he said. "But at this point, we've got no choice. The lava's not going to get tired. We are."

They hooked a sharp turn off the trail. The lava flows closest to them kept going, passing them, at least for now. Rebecca slipped and went down. Mac pulled her up, then he removed a tool from his utility belt, an infrared thermometer, and held it toward the rocky mass directly ahead of them, which was clear of lava for the moment. He found a long stick that had fallen from a koa tree and tapped it on the surface, checking for hollow tubes where lava might be pooling underneath.

"Feels solid," Mac said, "but the mountain's interior temperature is rising. It's about six hundred degrees now. Our boots won't melt until it's about eight hundred, so we can keep making our way down."

Rebecca, who had looked more surefooted than Mac initially, took the lead and nimbly began to weave around masses of lava rock.

Mac thought: The ground is too weak. Right fucking here. "Rebecca! Stop!"

A hole in the earth opened up a few yards ahead of Rebecca.

What had just appeared without warning was a skylight. When quakes and tremors made cracks and fissures in a lava field, the ground could split open like a trapdoor over an air gap with lava flowing beneath it.

But Rebecca didn't see it because at that moment she half turned and said something to him. Mac screamed, even louder, "Stop!"

Rebecca didn't hear him—she faced forward again, the skylight right in front of her, and tripped over a large rock.

As Mac reached for her, she started to fall.