Black-17 was fully charged when the alert came in. The sleek black security Roomba slid from its charging station and joined six others to investigate the disturbance. Sound had been picked up in the outer offices that didn't match the normal profiles of permitted sounds. This had happened more and more over the years, adding new sounds to the list. Just last month, moisture from the hydroponics section had leaked through the ceiling, and a tile had fallen after decaying slowly for years. Before that, the double-sided tape used to hold a calendar to an office wall had failed, sending the yellowed calendar with pages of penguins to the floor. That had caused a full-scale alert with all seventeen remaining security Roomba patrolling continuously for a week. That was when Black-3 and Black-11 were lost, victims of too much dust and too little maintenance.

As Black-17 moved down the hallway to the main doors of the outer office complex, it left a trail in the dust that coated the corridor. Security Roomba had upgraded batteries and lasers, with no room for normal cleaning attachments. Requests to the main facility had been made for replacement cleaning Roomba, with no answer. The security Roomba had soldiered on, noting the increasing difficulty of movement and the wear and tear on their gears. On the first of each month, they requested replacement parts, a repair tech (with appropriate clearance), and cleaning Roombas to take care of the growing dirt problem caused by the hydroponics area and courtyard areas. No one ever replied.

As Black-17 arrived at the outer office area, it was noted that the noises were coming from the access portal to the main facility. Someone was requesting access and making the overhead speaker beep repeatedly. The speaker had seen better days, and the new sound had triggered the alert. Black-17 noted a fleet of twenty-two cleaning Roomba, one of which was guiding a cart piled high with boxes and an electronic manifest stating they were delivering the requested spare parts. Nothing was mentioned about an approved technician to make the repairs. Black-17 unlocked the security doors and allowed the cleaning Roomba to enter. A red light above the door began flashing as air quality sensors registered argonite gas mixing with the normal air mixture of the VIP quarters. Air was pushed into the corridor to create outward air pressure to push back the invading gas.

The worker machines took one scan of the hallway, made rapid beeping noises, and got to work, sweeping up the accumulated dust and dirt. Others followed behind, polishing the hallway. The cart moved forward, propelled by its internal electric motor, but stopped in the middle of the doors and shut down. The security Roomba rolled around it, aggravated by the breach in the perimeter. The cart ignored them, its wheels locked and its heavy load of parts keeping it in place. A machine was requested to move the broken carriage, and shiny black security Roomba lined up to guard the entrance.

They'd only been guarding for five minutes when the intruder appeared. At the other end of the hallway, a tall humanoid figure with outstretched arms holding obvious weapons moved into view. The helmeted head made sounds that the Roomba noted as laughter, a human-made noise with zero information content. A long robe covered the human from its neck to past its feet. It glided forward, laughing and waving its arms. The Roomba gave several recorded warnings and then started firing. The intruder fired back, spraying light from each hand across them. High-powered lasers that should have killed any human repeatedly hit the intruder. After a minute of laughing, it yelled in a mechanical voice, "I am the Dread Intruder; there will be no survivors!" Intensity was increased from 7 to 8, and then 10. One by one, the security Roomba ran out of power as the Dread Intruder advanced until only Black-17, 13, and 3 were left. With a last hit, the intruder stopped, charred and in pieces, revealing a steel manikin standing on a non-standard crawler. The poor crawler ceased moving when Black-3 shot low and removed its power core.

From behind the remaining security drones, eleven of the sweepers lined up and, on Max's order, fired on the Black Roomba, destroying them in one volley. Milo ran around the corner, leaped over the cart, and into the outer office area. "Great job, Max. You guys, too." Only Max beeped back. Rusty had helped him upgrade the programming on Max. He wasn't fully intelligent yet, but he was smarter than the average Roomba. Noting that these rooms had a normal air mixture, Milo pushed the damaged crawler forward so the doors would close and seal. Fans turned on, sucking up the air in the corridor and replacing it with breathable air. The next task was following his Roomba brigade to the charging area, where he carefully unhooked the security Roomba and turned them off. They needed new programming before they would be safe.

Now that he was inside the VIP area, he was anxious to see what was there. A long hallway ended in three sets of double doors in each direction. Along the way were office spaces. These were stripped of paperwork and computers, but not as completely as the rest of the facility. He'd search for clues later. Right now, he wanted to explore. He wasn't entirely sure what was in this section, but the fact that it had breathable air was a nice benefit. For now, though, he'd keep his helmet on.

The VIP section was tucked into a corner of the facility on the five floors at the top. Rusty had limited information on it, but the official designation of Emergency Survival Bunker 017 implied a few things. It was a separate part of the facility with its own air, power, and security systems. Rusty was a bit upset when he told Milo all he knew about it. The A.I. felt that this was his home, and he didn't like hiding things in corners. Milo was only too happy to investigate and discover the hidden area, especially after Rusty told him there was an elevator leading up to the Habitat. Access to the elevator had to be where the VIP area touched the support structure and was hidden inside the hollow structure, similar to how the air intake and exhaust systems were inside other supports.

Milo was curious about where the elevator would take him in the Habitat, but he had an idea. If this elevator was intended to bring people down to this facility, it had to exit near one of the main entrances or on top of the Habitat. The topmost floor of the Habitat was mechanical systems that worked with the wind and solar generators on the roof, but under those were two floors of administration offices that saw little use. The people responsible for the Habitat's overall operation were in cozy offices elsewhere, with access to the rest of the world, not living in Habitat and eating processed food. And, if he remembered correctly, there was a large helipad near that corner of Section E. He'd wanted to use the large flat space to set up the solar panels he had purchased but had to move them elsewhere when he saw what the area was used for. It made sense to him that if an actual group of VIPs were coming to the Habitat, flying in on a helicopter or VTOL aircraft and taking a hidden elevator here would be the fastest and most convenient way to get to Emergency Survival Bunker 017.

The charging stations for the black security Roomba were in the last room before the three sets of sealed double doors. While several computers had been removed from the room, Milo found that he could simply plug into the vacant connection. He found a working security system that instantly challenged him for a password. It proved simple to hack the security system. He downloaded the maps of the area and access codes to his Roomba and made them part of the system. Immediately, they were given hundreds of tasks involving cleaning and disposing of trash. He had them hold off on the work for now. Things a Roomba thought were trash might be a clue to what this area had been used for.

The map of the area was interesting. The center area was large and five stories tall. It had the odd name of The Promenade. He was currently on the bottom floor. To the right and left, the double doors opened on hallways that moved around the perimeter of the large area. The outer perimeter comprised large rooms two or three stories high with odd names: Multi-use Recreation, Gymnasium, Cinematic Briefing Room, Aquatic Recreation Center, and Media Center. He vaguely knew what the words meant because the Habitat had similar areas, but all were empty, dark, and had never been built out. Two were obvious: the Medical Center and Dining Hall. And in the top level, in the corner where the two outer walls came together at the support, was a large room labeled Restricted Topside Access. Access to that was a hallway on level 5 that led to an area that was part of the center area. The map was confusing about where the access was to that area, so Milo decided to explore the large central area first and figure it out.

"Onward, my brave scouts. Take me to The Promenade." Max led the way to the center set of doors, which opened to a series of beeps. Milo stepped inside and stared...not believing what he saw. Birds were chirping, and the sky was blue overhead, impossibly high. Houses ringed the central park, where a small fountain shot water into the air. Several trees reached for the skies while below, bushes and grasses had overgrown what had been a park. A cobblestone road circled the park and ran in front of the wood and brick houses that looked down onto the park.

A carved wooden sign on a post with yellow and white paint cheerfully declared: Welcome to Downtown!