The Vault was known formally as the Patent Registry Models and Samples Repository. But everyone just called it the Vault. It was down below the Registry’s offices: very far below. There was a smart way, and a fast way, to get down there. Nobody took the smart way.

So instead of climbing down six flights of stairs, Ben just took the elevator.

There hadn’t been a serious incident down here in a couple of years, so the chances that he’d get stuck in the elevator were very small. Once again, the fast way turned out to be the best choice.

Of course once you pass the heavy, shielded doors at the Vault entrance there isn’t an elevator any more, and so if you needed to get down to the most recent (and lowest) levels the stairs were your only choice. Ben passed the checkpoints with one finger pointed at his investigator’s badge. It was a formality, anyway, but the guards were strict about regulations.

New Patent Officers rotated through Vault duty once a month, but as soon as they got down here they acted the same way that Vault guards had always acted. He’d never figured out how they did that. They seemed perfectly normal once they’d rotated out again.

There were currently twelve Vault levels. The twelfth was still under construction, so Ben knew that he’d find Officer Rocklynne down on Eleven.

What he found first was a crew of child-sized robots who looked like a cartoonist’s idea of an ancient Greek warrior. They had heads like stylized helmets. The sweeping, streamlined shapes of their bodies and limbs all looked a little like pieces of armor. Ben had no idea what model of robot they were, but they looked sort of familiar.

The crew was wrestling with a very large apparatus of some kind, spiky with glass tubes and stoppered valves. The robots were making up for their small size through the use of levers and a wheeled platform, but Ben didn’t like the way their levers jerked back and forth around the machine’s glass tubing.

“Hey!” he said. “We’re not playing around here. Be careful!”

The robots froze in place, except for the nearest, who dropped his lever and hid his face. The rest all stared at Ben through their impassive lenses.

He hurried over to pick up the dropped lever. “I’m not kidding!”

The little robots seemed to tense: it was something about the way their shoulders crept inwards while they half-stooped into defensive postures.

Ben handed the lever back to the nearest cowering robot.

“Stowing these inventions is serious business. It’s not a game.”

The robot rushed off toward the stairs while Ben stared after him in disbelief. He turned back to the others, who were still watching him silently.

“Didn’t they train you fellas?” he asked. “Didn’t they tell you not to horse around down here?”

Another robot broke away and high-tailed it down the corridor.

“Look,” he continued, “I’m not trying to scare you. But these things are dangerous.” He tapped one finger on the machine. “They’re not toys.”

A third robot dropped his lever and ran, wailing in a soft, melodious voice.

Ben backed away. “Okay, not sure what the problem is here, but just take care with this thing, will you?”

The remaining robots were hunched over, their little eyes blazing with yellow light. They were gripping their levers with a focused intent that Ben was beginning to find unsettling.

“I’ll, uh, I’ll just go now, then,” he said, and that’s what he did.

When he saw Officer Rocklynne up ahead, he started to say “What’s with the –” but then he saw what Rocklynne was dealing with. “Oh, my.”

In most of the area of a Vault level there were rows and columns of shelves, variously sized, and it was on those shelves that the Registry filed the models and samples for every invention that had been patented. The levels were large, and there were a lot of them, but it was the space between these working prototypes that was crucial. You didn’t want a Transdimensional Magnetic Field Generator anywhere near an Antimagnetic Atomic Repulsor Array, for example; and in fact that was the example that was used in the training film that officers and investigators sat through before they were allowed into the Vault. Each prototype was documented and tested before it was assigned a space on the Vault shelves, to prevent the kind of trouble those two devices had caused by their surprising interaction in the Registry’s original Vault, which had been located under the Registry’s original building.

All this was standard. But there were some devices that just couldn’t be classified as safe when they were stored next to any other device. These prototypes were stored in sealed, reinforced mini-vaults that were set apart from normal shelving. The mini-vaults had been certified as invulnerable to any existing or any possible contraption. This had always seemed like a tall order to Ben, and Officer Rocklynne was now shoveling sand onto the proof that Ben had been right.

Regulations specified that the free-standing mini-vaults should be built with five feet of clearance between them. It looked like they’d need to amend those specifications sometime soon.

“What are they?” Ben asked.

Rocklynne pointed his shovel at the right-hand mini-vault, whose near wall had crumbled under a thick, oozing layer of blue slime. “Low-Velocity Viscosity Projector,” he said. Then he pointed at the mini-vault next door. “And Universal Electron Inverter.”

Ben quickly thought through the possibilities if the slime generated by the Low-Velocity Viscosity Projector should ever break down the wall that protected the Universal Electron Inverter.

“That… it might… No. No, I don’t know what that would do,” he said.

“That’s why you need to pick up that other shovel,” Rocklynne told him. He dumped a shovelful of sand over the slime.

Ben picked up the other shovel and dug into Rocklynne’s pile of sand. “Containment Squad coming?”

Rocklynne nodded.

Behind them, Ben noticed that the crew of little robots had caught up to him, shouldering their levers to propel their load. It looked like they were still short-handed.

“You boys doing okay there, now?” he called.

Officer Rocklynne shot him an angry look. “Are you trying to get us killed?”