The trouble with rules, Jasper discovered, was that understanding them did not always make them less interesting. The lower-dock restriction had been easy to ignore when it was only a sign. After Deepwater, it became a sign connected to an old accident, unusual marine magic and a student who had believed they could control something they did not understand. This did not make Harper less curious. It made Ava more curious, which was considerably more dangerous because Ava knew how to use catalogues.

"We are not going through it," Ava said.

The three of them were standing in the corridor beside the lower-dock access door after lunch. Harper claimed they had been passing nearby. Jasper did not point out that the dining hall was two levels up and almost the length of the Academy away.

"I didn't say we were going through," Harper said. "We're looking."

The door was dark wood reinforced with metal bands. A silver ward plate had recently been fitted beside it, and beneath the plate a smaller brass notice listed supervised hours for younger students. Ava crouched to inspect the frame. "This part is newer."

"You can tell from wood?" Jasper asked.

"The hinge screws are different."

Harper looked at him. "This is why we keep her."

"I can hear you."

"Good."

Jasper's attention drifted to the stone around the doorway. The blocks nearest the frame were pale and recently cut, but one section farther back carried shallow marks almost erased by time. He stepped closer.

"Ava."

She looked up.

"Is that writing?"

The three leaned toward the stone without crossing the red boundary line. Under several layers of repair marks were four angular characters. Harper squinted. "Selari?" Ava took out her notebook. "Definitely older script." Jasper recognised one character from class and felt absurdly pleased about it.

"That one is water. I think."

"Sava," Ava said.

"Right."

"Maybe," Harper added helpfully.

Ava ignored her. "The second character looks like the old form Professor Ilyan showed us for boundary or threshold."

"So it says water door?" Harper asked.

"No. That is not how translation works."

"It would be a good name."

They were still arguing when the ward plate flashed once. The lock clicked. All three froze. The door opened two centimetres. Cold, salt-heavy air breathed through the gap. Nobody touched it. Harper's face changed from delighted to cautious so quickly Jasper almost missed it.

"Did you do that?" she whispered.

Ava shook her head. Jasper felt the pressure behind his ribs. Faint. Deep. Familiar. He took one step backward. The door remained slightly open. Professor Ward's voice came from behind them. "That is an impressive collection of guilty expressions." They turned. Ward walked toward the door, took in the ward light and the gap, and became serious at once.

"None of you touched the plate?"

"No," Ava said.

"Crossed the line?"

"No."

Ward checked the ward with a small brass token. The plate flashed red, then blue.

"Back to the main corridor."

Harper opened her mouth.

"Now."

That ended discussion. The door was closed and re-warded before dinner. By evening, a temporary notice had appeared instructing everyone to use the eastern stair for supervised harbour access until maintenance finished inspecting the lock. Professor Ilyan found them in Ancient Selari the next morning and wrote the four characters from the door on the board.

"I understand some of you discovered these yesterday."

Harper looked toward Jasper. "We're famous."

"You're loud," Ava corrected.

Ilyan tapped the inscription. "The best current translation is not water door." Harper looked wounded.

"It is closer to: where the water passes, wait."

Jasper stared at the words.

"A warning?"

"Possibly. Or an instruction. The grammar predates several standard forms. Context matters."

Ava wrote every word. After class, Jasper copied the inscription into his own notes. For the first time, Ancient Selari did not feel like a school subject somebody had added because old languages were respectable. It had been cut into Tidefall's stone before the present door existed. Whatever people here had been dealing with, it had started long before him.

The problem with rules was that some of them became more interesting after you understood why they existed. The lower-dock rule was one of those. Before Deepwater, it had been a sign. YEARS ONE TO THREE: STAFF SUPERVISION REQUIRED.

After Deepwater, it was a sign connected to a twenty-three-year-old event involving unusual sea magic, a student making a dangerous choice and someone getting hurt. This did not make Harper less interested. It made Ava more interested, which was much worse.

The door was ordinary dark wood reinforced with metal bands. Beside it, a small plaque displayed access hours and rules. Year Four and above could use the lower docks during daylight open periods after completing marine safety training. Years One to Three required staff supervision at all times. Temporary red closure notices overrode everything. There was no ambiguity. Ava read every line anyway.

Ava shut the notebook. That should have been the end. Then the door clicked. All three stared. The handle moved down by itself. Not fast. Slowly. The latch released. The door opened two centimetres. Cold salt air moved through the gap. Harper's eyes widened. Ava whispered, "We didn't touch it." Jasper's chest became heavy. Very heavy. The gap widened another centimetre. From below came the distant crash of water inside the cliff harbour. Harper stepped toward it. Jasper grabbed her sleeve.

That evening Thorne came to Room Fourteen. Headmasters did not normally come to first-year bedrooms. Harper immediately sat up straighter. Ava moved three papers off Bag Bed. Jasper stood beside his bed. Thorne remained near the door. That thought should have made him feel less responsible. Instead, it made the Academy seem much older beneath his feet.