She pushed another ancestor into her timepiece and another one into her compass. She explained to the rest what computation she wanted each of them to perform. She opened her navigation book and sped through the tables until she found today.

“Four minutes,” chimed the timepiece. They might already be too late.

Another barrage rocked the ship, sloughing time. Faster.

“Give me numbers!” Isabelle commanded, touching the devices one at a time, feeding the numbers to her waiting throng of ghostly computers.

Twenty-seven point nine five three, said Capitana Falconé, who had been selected to give the final result.

“Three minutes,” chimed the timepiece.

Isabelle checked her previous calculations. Her soul felt like it had been ripped out. Too late … unless …

She sprinted for the quarterdeck and the wheel. “Hard to starboard!” she shouted. “Take us straight at the wall! Pressure to the keel!” They needed speed that wind couldn’t give them.

The helmsman threw himself into the wheel. The rudder flexed and the ship turned. Isabelle peered through the smoke at the shrieking veil of wind, looking for the escort. Logic insisted it was a good thing she could not see one yet.

A great dark shape cast a shadow over her. She looked up just as Bitterlich landed beside her, all black wings and sinewy body. He shifted down into his ordinary shape.

“How are we doing?” he shouted.

“That depends on how much you trust my arithmetic!”

The light dimmed. The sky closed in and a wall of sleet turned all shapes into shadows. The frigate kept up its fusillade, falling behind. The Saint Asne hooked into the Bittergale’s outer wall and began to accelerate. The third sloop gained on them.

Hailstones whipped across the deck, clawed at the rigging, and pummeled the strakes. Where in all the uncharted skies was that cursed escort? Had she miscalculated?

Rebecca popped up from belowdecks, flush with victory. “Did you see me catch that spar?”

The sleet tapered off as an enormous shape emerged from the fog on their larboard side. Isabelle’s breath caught at the sheer immensity of it. The escort was like a mountain tumbling through the sky, but no mere rock was this. Isabelle’s l’Étincelle spark swarm flared in its presence, recognizing a quondam artifact, albeit one layered in accretions of ice, snow, and stone.

“Larboard!” Isabelle shouted to the helmsman. “Vent the forward keel chambers!”

Similce looked at her like she’d gone mad, but relayed the order without delay.

The Saint Asne drifted sideways, sliding into its vortex. The timbers groaned as the ship tilted nose down and fell forward, accelerating. Ships were never supposed to be pitched down like this. Sliding forward under gravity not only risked backing the sails, but if the forward tip of the keel dipped too far, the ship would flip vertically and javelin into the Gloom.