“Give me a minute to check the GPS.” After a minute, Sam said, “We’re on it. They would have watered their horses along the riverbed. And if I were a nomadic horseman, I would be sure to take really good care of my horses.” He turned away from the river to face the field. “Fifty to a hundred thousand Hun warriors means something near two hundred thousand horses. It’s hard to imagine what that must have looked like. The line of horses must have stretched along both rivers for a couple of miles.”

Remi wheeled her bike to a nearby tree, leaned the bike against the trunk, stepped on the bike’s lower bar, then the seat, and pulled herself up to the tree’s first large branch. She reached up to the second branch for a handhold and then stood.

“What do you see?” asked Sam.

“From up here, it looks as though the highest part of the field is right over there.” She pointed a hundred yards inland to a section of the field that was slightly elevated.

Sam stepped close and helped her down, then extended the magnetometers’ poles so the sensors extended about three feet in front of the bicycles’ handlebars and the boxes holding the gauges were between the handlebars and easy to read. They walked their bicycles, side by side, into the field and up the slight incline.

It was late afternoon, the sun’s rays falling at a low angle on the field. As they walked they read the magnetometers, watching for disturbances in the magnetic field. There was little fluctuation in the readings until they crossed the highest point in the field, which was almost a dome. Then the needles jumped.

“Did you get that?” Remi asked.

“Got it,” Sam said.

They both stopped. Sam said, “Let’s see how big it is.”

Remi laid her bike down to mark the place where the disturbance began and walked with Sam as he wheeled his bike a few yards. “There,” he said and laid his bike down. They paced the distance together, then replaced the bikes with their sun visors. They rolled the bikes along a perpendicular path. “It’s ten paces by fifteen,” Remi said.

“That’s what I get,” Sam said. “About twenty by thirty feet. Let’s try one of the metal detectors.” Sam assembled the one from Remi’s backpack and began to pass it back and forth over the area they had marked off. It gave off an electronic tone, then a squeal—a loud and unchanging shriek—as he walked the width of the spot.

Remi said, “It’s huge—much bigger than the first chamber. Plan A or Plan B?”

“We’ll have to mark it so we can find it again quickly, then ride back to Peschiera del Garda and get ready to excavate tomorrow night after dark.”