Below the Breathable Limit

Mara had no time to turn the page.

The dull thunder of a pressure mortar shook the timberwork from stern to keel, wringing an agonizing shriek from the master frames. The black oilcloth notebook went flying toward the drainage grate, but Mara threw herself onto the sheet-metal floor and snatched it to her chest before the bilge soup could swallow it. Overhead, through two decks of oak and wrought iron, a dry, metallic crack echoed, as if a gigantic steel centipede had just dug its legs into the crown of the quarterdeck.

Boarding hooks.

"Damn their bureaucratic breed!" Onofre Cuesta roared from the vent corridor.

The old machinist appeared stumbling, the flat wrench gripped in his right hand and a fresh smudge of soot cutting across his wrinkled forehead. He limped with more rage than pain, dragging his clumsy leg while a jet of steam hissed like a viper behind the bulkhead.

"Have they caught us?" Mara asked, forcing the notebook into her frayed canvas rucksack. The zipper, broken for two winters, snagged on the middle teeth as usual. "I thought the closed-circuit purge left no trace in the milky layer."

"And it doesn't, brat, unless the hound hunting you has his nose glued to your wake. It's Arteche's corvette, the Harbor Office's bloodhound. I recognize the snap of his compression mortars from ten leagues away. He's trimming the high stratum, nice and clean above the muck, throwing iron at us to leash us in tight."

The deck shuddered violently once more. From the ceiling of the bilge fell flakes of rotted wood and a fine rain of alkaline saltpeter that hissed over the hot plates.

Mara adjusted her flight goggles over her forehead. The left lens had a diagonal scratch and the leather rim smelled of old sweat, but they were hers. In her jacket pocket she still carried two crushed rye biscuits; she pulled one out with her fingertips, broken into three earthy pieces, and shoved the largest one into her mouth by sheer inertia before getting to her feet.

"Are you hungry now?" Onofre growled, blinking with annoyance while he adjusted the mercury pressure gauge of the auxiliary boiler with a few blows of his fist.

"It was going to fill with sulfur dust," she replied, chewing with difficulty. "Do you want half?"

"It has lint on it."

"Then don't eat it."

Onofre clicked his tongue, snatched the piece from her grease-stained fingers and swallowed it in a single bite without taking his eyes off the needle trembling in the red zone.

A new tremor, more prolonged and screeching, tightened the bracing cables that ran down the walls of the hull. The imperial corvette's grapples had bitten firmly into the exterior woodwork. The whistle of steam in the lead joints changed pitch, turning into a hoarse, high-pitched gasp.

"He's towing us toward the clear quota," Mara said, pressing one hand against the vibrating frames. She felt the pull in her palms: the entire ship was protesting, hoisted by the nose toward the regulatory light where the imperial patrols hunted at will. "If we leave the cloud, we're dead."

"And if we stay here, those hooks will snap our backbone in ten minutes," the old man retorted. He scratched his gray beard, leaving a white trail of saltpeter over the coarse hairs. "That Arteche isn't shooting to kill. He wants the whole ship. He wants what your father left tucked in here."

Mara froze with her hand still resting on the wood.

"Does he know?"

"Arteche knows even the brand of tobacco the stokers smoke in San Telmo, little one. Do you think your father hid in this bilge for a month just to change screws? Don't be a fool. He looked at every rib of this old shell."

The brass speaking tube connecting the secondary bridge to the bilge burst into a dry whistle. The bronze tongue danced like crazy inside the mouthpiece.

Mara and Onofre stood motionless. The only sound in the ochre gloom was the rhythmic dripping of burnt oil onto a zinc tray and the distant creaking of the boarding chains tightening against the waist.

"Don't pick it up," Mara whispered.

"No need," Onofre said in a low voice. "That piece of junk has the horn wide open."

A metallic clearing of the throat resonated in the brass bell, neat, leisurely, with the hollow echo that only the resonance amplifiers of the imperial officer corps could produce. Íñigo Arteche spoke as if he were sitting in a teahouse on solid ground, measuring each consonant with the precision of a drafting compass.

"Bilge four," Arteche's voice said, crisp and freezing. "I know you're listening, Cuesta. And I know perfectly well who is handing you the tools this morning."

Mara's left bootlace came untied. She looked down at the loose bow on the pitch-stained floor, but she didn't bend down. She didn't even dare to breathe.

"You have no maneuverability," the speaking tube continued, accompanied in the background by the rhythmic heartbeat of the imperial corvette's pistons moored at her back. "My winches have your stern gripped. If I apply pressure to the draft boilers, I'll tear your rudder away in three minutes and you'll drop to the bottom like an uncontrolled bale of lead."

Onofre leaned toward Mara and pointed his chin at the starboard bulkhead.

There, beneath a layer of dried grease, hung a forged lever painted in faded yellow. The valve of the secondary ballast tanks. Three steps away.

Mara knew the unwritten rule of the boilermakers, the one her father used to repeat when he drew keel sections on wrapping paper: the ship that swallows the heavy fog drops like a stone, but the ship that falls too fast never comes back up.

"Ibarra," Arteche's voice called from the tube, with a gentleness that was sharper than a boarding ax. "Your father was a competent craftsman, but he made the blunder of believing the Crown's secrets fit in a waistcoat pocket. I know what he carved into the master frames of that hold. Hand over the logbook and the coordinates he carved into the oak. In exchange, I'll lower a rope ladder. Absolute immunity for you and a clean disembarkation passage in San Jerónimo for the old man. You have ten seconds before I order a hard turn."

Ten seconds.

"The lever," Onofre murmured without moving his lips, locking his tired eyes onto the girl's. "If you pull it down, Mara, we're going straight to hell. At three thousand fathoms beneath the regulatory sky, the air tastes of copper and there is no paper left where one might sign a pardon."

Mara didn't wait for Arteche to count to three.

She leaped onto the damp timberwork, ignoring the loose loop of her boot lashing at her ankle, and hung with both hands from the flood lever.

The iron offered stubborn resistance, seized by weeks of accumulated saltpeter, but Mara threw all her weight backward, bracing her heels against the base of the auxiliary boiler. The sheet metal groaned. A spring snapped with the dry sound of a gunshot and the valve yielded downward in a jerky, greasy motion.

A deafening roar shook the bottom of the ship.

The lower hatches burst open to the Foam. Tons of dense, sulfurous gas flooded the blind tanks, and the galleon, freed by the brute force of its own dead weight, ripped two of the corvette's hooks straight off in a shower of splinters and broken links.

They fell in a steep dive.

Mara's stomach floated inside her chest as gravity vanished beneath her feet. Through the speaking tube, before the sulfurous vapor choked the air ducts and drowned the brass in a foul gurgle, Commander Arteche's voice filtered through static crackles once more:

"Drop all you want, Mara. There is no bottom where I cannot find you."