The inheritance of the silent starship changed everything. The secrets locked away in Elara's data slate and the promise of a galactic seed bank transformed Alex's mission from a desperate struggle for survival into a staggering project of world-building. But the promises of the future were still buried under two millennia of silt and seawater, and his people were starving in the present. The discovery was a key, but he still had to unlock the door.
The energy in the Emperor's study was electric. Alex, Maximus, Sabina, Rufus, and Perennis were gathered around the desk where the laptop sat, its screen glowing. They had become a true, albeit deeply strange, council of war, their individual mistrusts and rivalries burned away by the sheer, overwhelming magnitude of what they had found.
Lyra's voice, now at full power thanks to Elara's chrono-crystal, was crisp and authoritative as she displayed a 3D schematic of the crashed vessel on the screen. The image rotated slowly, a ghostly wireframe of an impossible object.
"I have completed my analysis of Elara's engineering logs," Lyra stated. "The primary cargo hold, containing the xenobotanical archive, is located in the mid-section of the vessel, here." A section of the ship glowed bright green. "The main cargo bay doors are fused shut, likely from the heat of atmospheric entry during the crash. They are inoperable."
A grim silence fell over the room. "So we have found a treasure we cannot reach?" Rufus asked, his voice heavy with disappointment.
"Negative," Lyra replied. "Elara's logs indicate a secondary, smaller access point. A maintenance and loading hatch, here, near what you would call the stern." A smaller circle on the schematic lit up. "Its position corresponds with the area your engineers have already been excavating at Ostia. However, the logs indicate it is sealed with a high-tensile pressure lock and is currently buried under approximately thirty feet of compacted silt and Roman-era landfill."
Maximus slammed a gauntleted fist into his open palm. "Then we will dig. I can have a full cohort of military engineers at the site by dawn. We will use cofferdams to hold back the water and excavate down to the hatch. It may take months, but we will reach it."
"We do not have months, General," Sabina countered, her voice sharp and practical. "The city has weeks, at best, before the grain riots turn into a full-scale civil war. Furthermore, a project of that size—a massive dam and excavation in the middle of our busiest harbor—would be impossible to keep secret. The entire Senate would know we were doing more than 'sanctifying a cursed site.' Lucilla would have a thousand new questions."
She was right. They were caught between a slow, public solution and an immediate, desperate need.
Alex looked at the schematic, his mind working, processing the variables. Roman engineering was powerful but clumsy, relying on brute force. Elara's technology was elegant but inaccessible. He needed something in between. He needed a hybrid solution.
"We will not hold back all the water," he said, an idea forming in his mind, a fusion of Lyra's science and his knowledge of ancient principles. "Just the water directly around the hatch." He turned to his council. "We will build a caisson."
The others looked at him, confused by the unfamiliar term. "It is a concept from the old Greek engineers," he lied smoothly, a plausible origin story for the technology. "A massive, open-bottomed, weighted wooden box. We will build it on the surface and sink it over the target area. The weight of the box, combined with the immense pressure of the water outside, will create a seal against the mud of the seafloor."
He sketched the design on a piece of papyrus. "Then, using a series of Archimedes' screws, powered by teams of oxen on the surface, we will pump the water out of the caisson. We will create a pocket of breathable air at the bottom of the harbor, a dry chamber around the hatch. It is a faster, more discreet method than building a dam."
It was a high-risk, high-tech (for the Romans) underwater construction project, fraught with danger. A single leak, a single structural failure in the wooden box, and the men inside would be crushed and drowned in an instant. But it was their only viable option.
The "New Machine" of his government roared to life, its members now united in a single, incredible purpose. Sabina, with her unmatched logistical genius, procured the vast quantities of timber and lead weights needed for the caisson, using a dozen different shell companies and shipping manifests to ensure no single merchant could piece together the scale of their project. Maximus's legionaries, sworn to secrecy, provided the disciplined labor, working day and night to construct the massive wooden box on a hidden stretch of the coast. Senator Rufus handled the legal and political cover, securing the necessary permits from a terrified Senate for the construction of a "new lighthouse foundation to honor the Emperor's safe return from the sea." Perennis's spies moved silently through the port of Ostia, a network of whispers and shadows, ensuring the project remained secret and dealing quietly with anyone who became too curious.
And at the center of it all was Alex, orchestrating the complex operation with Lyra's guidance. Timo, his devoted acolyte, faithfully tended the "sacred fire" of the thermoelectric generator, ensuring Lyra had the constant, stable power she needed to run the complex engineering calculations for water pressure, structural integrity, and buoyancy.
After a week of frantic, round-the-clock work, the massive caisson, a wooden structure the size of a small temple, was complete. It was towed into position and slowly, carefully, sunk into place over the target. The sound of the oxen turning the massive screws of the Archimedes' pumps became a constant, groaning feature of the work site as thousands of gallons of water were lifted from the depths and poured back into the sea.
The day came to test their creation. Alex, Maximus, and Sabina descended in the diving bell, this time landing not on the seafloor, but on a wooden platform built just above the water level inside the newly-pumped caisson. They were in a strange, man-made cavern at the bottom of the harbor. The air was thick, humid, and smelled of wet wood and disturbed mud. The walls of the caisson groaned under the immense pressure of the sea outside. Below them, a team of Maximus's legionaries worked in the knee-deep mud, their torches casting flickering, hellish shadows.
And there, in the center of their dry pocket of the abyss, was the hull of the starship. And set into it, now free of the silt and water, was a large, circular hatch, its dark, alien metal gleaming in the torchlight.
"It's sealed shut, Caesar," Maximus said, his voice echoing in the cavernous space. "Tighter than a vault. We will need siege equipment, a battering ram, to break it open."
"No," Alex said, his heart pounding. He had come prepared for this. "That would be like trying to open a locked door with an axe." He waded through the mud towards the hatch, holding Lyra's final instructions in his mind. "Lyra found the external release mechanism in the ship's schematics. It's not a physical lock. It's a pressure-lock."
He ran his hands over the smooth, cold surface of the hatch. "It's designed to be opened from the outside in an emergency. The mechanism is keyed to a specific sequence of simultaneous pressure points." He pointed to a series of five small, almost invisible indentations around the rim of the circular door, arranged like the points of a star.
"We need to press these five points. Exactly at the same time."
He assigned a point to himself, one to Maximus, and one to a surprised but determined Sabina. Maximus called over two of his largest and strongest centurions to take the remaining two points. The five of them stood around the hatch, their hands poised over the indentations, the only sound the groaning of the wood and the dripping of water.
"On my mark," Alex commanded, his voice tight with anticipation. "Three… two… one… NOW!"
The five of them pushed, their combined strength pressing into the cold, ancient metal. For a long, heart-stopping moment, nothing happened. Alex's heart sank. Had Lyra been wrong? Had two millennia of pressure fused the mechanism shut?
Then, a low, deep, resonant hum started, a vibration that seemed to come from the metal itself, traveling up their arms and into their bones. A thin, blue line of light appeared around the circumference of the hatch. With a soft but powerful hiss, like the sound of a great beast exhaling after a long sleep, the ancient atmosphere from within the cargo hold escaped.
The massive, circular door, a piece of metal that should have weighed tons, did not swing open. It retracted, sliding silently and perfectly into the hull of the ship, revealing a dark, cavernous, and utterly black space beyond.
They stood at the threshold, staring into the darkness. They had opened the doomsday vault.