Austin had purchased a Hawaiian surf-print bathing suit at the dive shop, flaming orange-red with hula dancers, the only thing that the shop had in his size. He tucked his wallet and phone in the waterproof dive-gear bag and slipped into the buoyancy compensator, weight belt, tank, and fins. He rolled over the gunwale into the tepid water, came up and gave Song Lee a quick wave, then bit down on the regulator mouthpiece and did a surface dive that took him down several feet into the slow-moving brownish green water.

He switched on a waterproof flashlight he had bought at the shop. Visibility was limited in the murky water, but the light picked out the broken basalt that had once been the islet’s foundation. Austin swam around the perimeter, then came back up to the rental boat.

Whittles had suggested that the coral core supporting the temple had crumbled when the earthquake throttled the city, causing the building to sink to the bottom of the enclosure and the walls to collapse on top of it.

Austin swam around the pile again, this time at a different depth, and saw an opening where basalt slabs had fallen down at an angle. He poked his flashlight into the cavity. The light petered out, suggesting that there was open space behind. Austin twisted through the tight space, banging his air tank against the basalt.

Once he was through the passage, Austin swept the flashlight around and saw that he was in a cavelike chamber created when the inner and outer walls collapsed against one another. Even if the temple had not been destroyed, it was hidden behind the wreckage of the inner wall, which had fallen on top of and around it.

Austin thought he had reached the end of his explorations and was preparing to retrace his route when he made another sweep of the chamber with his light. This time, there was something peculiar about the way the shadows fell on the debris to his right. He swam closer, and saw that a slab had fallen and was blocking some columns, thus creating a breach.

Austin slithered through the breach, and, after swimming a few yards, came upon an almost perfectly rectangular entryway. The temple slanted down to the left, and the entry should have been plugged by debris except that its lintel had fallen in such a way that the opening was intact. He made a quick visual check to assure himself that the entryway wouldn’t collapse, then swam through it and into the temple itself.

Austin’s flashlight immediately fell on the pool that Whittles had described. It was rectangular, about twenty feet long and fifteen feet wide. Debris had fallen in it, but Austin estimated it was around six feet deep. Playing his light against one of the walls, he saw that he was not alone.