“So simple,” said Albrecht. “You think like a Roman.”

“I just hope they haven’t left guards on the surface to watch the site,” Remi said softly.

Albrecht said, “I say we take the chance. We breathe about sixteen times a minute and consume about twenty-four liters of air. We’d better get started.”

“Right,” said Remi. “Let’s lift Sam up to reach the slab.”

“No,” said Sam. “It would take both of you to lift me, but I can lift you both. If I brace myself against the wall, you can each step up on one of my knees, then to my shoulder. Push your shovel blade between the wall and the iron slab and pry it open an inch or two. That should be enough.”

“He’s right,” said Albrecht. “The two of us can exert more force than Sam can alone.”

Sam selected a spot, braced his back against the wall, and bent his knees. Albrecht and Remi took off their boots. Albrecht took a shovel, then stepped from Sam’s knee to his shoulder. Remi stepped on the other knee and shoulder. They worked the blades of their shovels into the crack between the iron slab and the stone entrance. They moved both hands down to their shovel handles for maximum leverage. Remi said, “On three . . . one . . . two . . . three.”

Sam didn’t have to wait to find out if his plan had worked. The fine, sandy soil that had made this such a perfect place for viniculture immediately began to trickle from the narrow opening that they had made. It soon fell in an unbroken curtain, coming down steadily, in front of his eyes.

Remi came down from his shoulder and helped Albrecht step down. Sam raised himself up and sidestepped past the falling dirt. Whenever the soil under the opening got to be a foot deep, the three would shovel it into the empty end of the stone chamber in front of Attila’s message. As the minutes passed, the level rose steadily, and they stepped up on it repeatedly, rising higher and closer to the ceiling each time.

Filling the stone chamber with dirt left less and less space for air. When the floor level had risen about four feet, Sam lifted his shovel and worked it up into the narrow space between the stone and the iron slab, increasing the opening, and then scraped along the wall’s edge, bringing more dirt into the crypt.

Remi said, “What are you doing?”

“Trying to speed up the process before the air in here gets too scarce. I’ve cleared a few inches of space so we can slide the slab into it and make a bigger opening on the other side.”

The three stood about a foot apart and pushed the slab the other way with their shovels. The slab moved on its rollers, first closing the narrow opening they’d made, then going another few inches. A much wider opening appeared on the other side of the slab, and the dirt sifted in much faster than before.