The door banged open, causing the wiry, brown-haired fourthling to sit bolt upright.

"Come on! Can't you hear it?"

Votsford Drave had been dozing lightly in his hammock, savoring a particularly welcome break. The night shift had been grueling, and a chilly wind had been blowing through much of this region of Middle Sky. Now he could hear the dull, blaring horn ringing throughout the cavernous central avenues within Twilight's Edge, audible even through the walls of his building.

"Damn and blast it all to open sky!" roared Votsford, springing out of his hammock, sheets flying, as he scrambled to get his uniform on yet again. "That's the third time that the emergency alarm failed to activate in my room! If you hadn't woken me, Dorfis, I…"

He listened to the horn for a second longer. "That's no ordinary alarm," he said.

"Emergency, code red," agreed Dorfis Dax. "Only one thing big enough to rouse all of Twilight's Edge…"

"The Vilnix Pompolnius," they said together.

The flagship of Vartolius Xax's fleet, captained by Imperial Governor Xelius Pulnix, the Vilnix Pompolnius was the biggest and most destructive glistership ever to take to the air. It was named after an ancient High Academe of Sanctaphrax—cunning, crafty, and corrupt—from which Xelius Pulnix was said to be descended. But since the first-ever Pulnixes who had settled in Great Glade had their roots in Undertown leaguesmen, no one was really sure Xelius Pulnix was indeed telling the truth about his ancestry. It didn't much matter.

Ever since the Vilnix Pompolnius had been constructed eighty-six years previously, unveiled during the centennial of the Empire's founding, the Vartolius Xax and his Phraxguardians of Riverrise had used it to assault Omniphrax. The Twilight Marines had always proved equal to it, driving it back every time, but with each new attack it sported formidable upgrades. Indeed, the Pirates Academic had lately been returning with reports that Vartolius Xax was presiding over the development of a new weapon called a 'glisterbeam'.

Once Votsford had put on his uniform, bearing the distinctive blue-and-gray stripes of the Twilight Marines, he and Dorfis dashed out of his room. Votsford, like most of the Twilight Marines, lived in one of the many vast residential complexes built into the Mire side of the great fortress. Now that everyone had been summoned to combat the invasion, they needed to get to the Phraxfields side of Twilight's Edge immediately. Down the flights of stairs they raced, past kitchens and common rooms and gymnasiums, until they burst through the doors leading to the central avenues.

The colossal space, with its aerial boulevards, had already changed. The sky ferries were no longer flying in every direction, but drawing steadily towards a point on the far side, just visible between the hundreds of maintenance towers separating the avenues.

Votsford and Dorfis joined a large crowd of Twilight Privates boarding a squat, wide sky ship. They managed to take the remaining two empty seats on the deck just as the ship whooshed away from the platform. The alarm still pounded in everyone's ears.

Votsford now noticed that not all of the sky ships were headed for the same spot after all. A few of them were traveling to points up and down the entirety of the Phraxfields side, to guard every region, even places that were nowhere near the predicted path of the Vilnix Pompolnius. In light of current events, there could be no question why.

Somehow, Empire spies had been slipping into Omniphrax in alarming volume. There were always a few who managed to get past Twilight's Edge—when an entire border has to be guarded, mistakes are inevitable—but now, it seemed like Empire agents were getting arrested every day, assassinating or attempting to assassinate academics. The leaders of the city had quadrupled security, and so far none of them had been attacked, but they didn't seem to be the targets. It was more like the Phraxguardians wanted to strike fear into the hearts and minds of those who were resisting them. And given the tension that had become palpable throughout Omniphrax, they were succeeding.

The moment their carrier landed, Votsford and Dorfis joined the teeming mass of Twilight Marines on the platform. Gradually, the crowd separated into smaller and smaller groups as everyone headed for different towers or gantries. Finally, Votsford and Dorfis arrived on a large, crowded scaffold looking out over the barren glowing mists of the Phraxfields.

Votsford gasped. The Vilnix Pompolnius was already there, not more than two thousand strides away and approaching fast, heading directly towards the section of Twilight's Edge where the two of them were standing.

"Earth and Sky!" he cried, moving to load a nearby catapult as quickly as possible. "How did it get this close before the alarm was sounded?"

"Incompetence?" suggested Dorfis, as he assisted three others with a massive phraxcannon. "Bad luck? Let's just concentrate on defending Omniphrax. We can ask these questions later!"

The Vilnix Pompolnius drew nearer still, and the party of Twilight Marines was nearly deafened by the shriek of the colossal glisterjets, each as large as the sky ship they had just ridden, and emitting a blinding scarlet glow. The metal energy conduits vibrated as they carried the power of the hundreds of glisters trapped within each jet-chamber to the six propulsion ducts. The construction of the hull, so unlike the lufwood and bloodoak architecture of the Omniphrax sky ships, was of buoyant, metallic lightwood, with a framework of heavy leadwood, engineered meticulously to ensure that the great glistership would be subject only to a mild downward tug of gravity. A great control tower protruded from the stern, surrounded by flat-topped structures. Built into the side of the hull were machines designed to launch all manner of deadly projectiles, and sliding bay doors further down the side indicated where the smaller swarms of glistercraft would be launched once the battle began.

Votsford knew that the battle would be bloody. The Pirates Academic would be on their way, but on such short notice it would take them a while to arrive. Until they did, the Twilight Marines would be on their own.

This wasn't how Votsford had imagined spending his day off.