“Saf’s decided Katu really has left Winterkeep without saying goodbye,” she said grimly, reading. “Katu left no forwarding address and his boat is gone. His family and friends say he’s off adventuring, as usual. Saf checked with Katu’s banker and apparently Katu’s drawn money from banks in Kamassar and Borza, with his own checks.”

“Well, that’s reassuring,” Giddon said.

“But how could he leave without canceling his appointment with Saf?” said Bitterblue. “And without writing to me?”

“Maybe he wrote to you and his letter got lost.”

“Yes, maybe,” she said, still deciphering the letter. “I hope so. Skye says here that Saf has been swimming with the silbercows.”

“The telepathic seals, or whatever they are?”

“They’re bigger than seals, and purple, but yes. He says the silbercows keep showing Saf an image of a many-windowed house on a cliff, and a shadow in the sky that looks like an airship. Then, a disturbance in the water nearby. A serious disturbance. Like, everything changes.”

“What do you mean? Changes how?”

“He says that in the image, the ocean is normal, then suddenly there’s a blinding light and no water and the silbercows are in pain.”

“Okay,” said Giddon, to whom that meant nothing. “All we need now is a vague remark about zilfium and the letter will be completely incomprehensible.”

“He says that now the Katu mystery is solved, he and Saf are going to Mantiper together. The Mantiperans are looking for a sea passage east to Lienid. Saf and Skye are going to join the efforts.”

Mantiper was the Torlan nation farthest from Winterkeep, so far east that Saf and Skye would likely be gone for a long time, sailing in uncharted waters. “That sounds dangerous.”

“Yes. But it sounds like they’re happy,” Bitterblue said with a small, winsome smile. “Ah,” she added. “Here’s a bit about zilfium. He says that no one in the Keepish government likes to talk about this, but the Torlan continent is running low on zilfium. Some mines in Winterkeep and Kamassar are closing.” Then she stopped, stared. Something changed in her face. “Giddon,” she said.

“Yes?”

“Saf says zilfium is most often found near native silver.”

“What does that mean?”

“Zilfium rock and native silver are formed by the same geologic activity. Where there’s native silver, there’s likely to be zilfium.”

“Okay,” said Giddon, not understanding why her face grew oddly furious. Then remembering that the largest and richest deposits of native silver on the Royal Continent were in Monsea.

“Do you think that the mountains in Monsea have zilfium?” he asked her cautiously.

“Would you excuse me for a minute?” she said, standing stiffly, so that the cat went sprawling.

“Of course,” he said, but she was already at the door, the cat yowling around her feet. A moment later, the door slammed behind them both.