And the Moon was not behaving as it was supposed to.

“Look up, Geena. We’re coming down short. Maybe you should take over and bring us in.”

“No. I told you. We’re autoland all the way to the ground.”

“Neil Armstrong did an override.”

“Neil Armstrong hadn’t been here before. We have. We have maps, Henry. We have photographs. Now shut up and let this thing land itself.”

A thousand feet above the Moon, and he was flying towards a bright field of craters, their shadows stretching away from him across the Moon. The Shoemaker was coming in at a low angle, unreasonably quickly, like an artillery shell lobbed across some ancient battlefield; and Henry was riding the shell, feet first.

Let Geena do her job, he told himself. Trust her.

But they were still coming down hard, and now there wasn’t even a sign of Apollo.

It seemed to Blue, now, that he was actually rising into the air, as if Dumfoyne was a raft which he was riding in a swelling lava sea.

Perhaps he should have brought an altimeter.

Lava from the main vent overwhelmed Strathblane, it seemed in moments. The neat buildings, the rich green fir trees, exploded and burned, as the lava, enclosed in a stretching sack of cooling rock, surged through the streets.

There were faults everywhere now, fissures and lava fountains. Already most of the vegetation had burned off. As if the whole area was turning into one giant caldera.

For now he was safe, here at the summit of Dumfoyne. The hill, and its nearby twin Dumgoyne, were little islands of stability, in a sea of fissures and vents and lava fountains.

Dumfoyne was a raft he was riding to the sky.

His voice transmission was still getting through, although his sky was covered, now, by an ugly, roiling cloud of steam and ash, through which lightning sparked continually. But the reception was too poor for his instruments” telemetry to penetrate, and, regretfully, he folded up his instruments and collapsed his laptop.

…incredible, Blue. We can’t believe these radar readings. There must be a magma volume production rate of millions of cubic metres a second…

That compared to hundreds of cubic metres, Blue knew, in an eruption of the size of Mount St Helens.

…as if we’re seeing a million years of geology compressed. Mauna Loa, built in a day. Mauna Loa in Hawaii was Earth’s largest volcano, stretching seven miles above the ocean floor.

“But this may be bigger than Mauna Loa,” Blue said, unsure if Sixt could hear him. “Bigger than anything on Earth.”

There had been no volcanism on Earth on this scale for a hundred millennia. Twice as long as humans had existed.

Perhaps this was Olympus Mons come to Earth, he thought. The giant Martian shield volcano, so huge its caldera poked out of the thin atmosphere. Mars, come to Earth.

The ground lurched, swelling further.