I notice his fist tighten around his bow. He says nothing.

“She means trouble for Styrland, Prince Gawain,” I say. “Whatever she’s promised your father, it will end badly. You want to protect your court? Help us. Tell us what you know.”

Gawain slowly lowers his bow.

“My father has had experts poring over your research since you disappeared,” he says. “At first, all he cared about was finding out how you made your gold, but then recently things changed. They were looking for something else. He sent his best metalsmiths and that awful jeweler, Radditch, to Faerie, and I couldn’t figure out why. All he’d done since you disappeared was curse the fae.” He glances at Ruskin, but keeps talking. “So I went snooping in your old workshop where they were working, but I got caught.”

He looks away, grimacing at the memory. I suspect Albrecht was not lenient with his punishment.

“That must have been unpleasant,” I say quietly, wanting to show him I understand. He swallows, gives a curt nod, and continues.

“My father was furious—but he also couldn’t help bragging about his rapport with the beautiful, powerful faerie queen.”

“And what about the experiments? Do you know what the jeweler and the others were working on?” I ask. I doubt Evanthe needed him to teach the metalsmiths how to make cold iron. And they certainly don’t need my notes for that. The missing piece is here somewhere, and I don’t think we’ll like it when we find it.

“I saw some of their research before I got caught.” Gawain shrugs. “It just looked to be a bunch of ingredients and calculations.”

“Think carefully,” I say. “What ingredients? Can you describe them?”

Gawain thinks. “There was salt. And some kind of blueish rock. Flowers too.”

I try to decipher his description, going over the long list of plants and minerals in my mind.

“Were the flowers little white ones, with long, round leaves?”

“Yes,” he says.

“Nitre bush flowers. And boothite. That’s what they’re using.” My voice is toneless as I put it together, because I suddenly understand.

“She’s going after the founding stone.”

Chapter 28

“How do you know that?” Ruskin asks, his voice heavy. He believes me, he just doesn’t understand.

I look at them all, feeling like an idiot for not thinking of it before. “I protected the stone with my magic, knowing no fae magic could undo it. But she’s not going to use magic. Thanks to Albrecht, she has access to men who can use science—my science. When you combine sodium, the mineral boothite and nitrus flowers, it makes an acid.”

“Acid?” Destan asks.

I shake my head, remembering that the fae don’t have words like this. It’s exactly why it didn’t occur to me that Evanthe would find this kind of workaround to my protections on the stone.

“It’s a liquid that dissolves,” I explain. “Something that can burn through even very strong substances. But you need the right type. Nitric acid will burn through metal, like the kind I used to protect the stone, but it won’t damage the founding stone itself.”

Ruskin’s face darkens. “How long would it take to make this acid?”

“If they have the ingredients? Not long at all. They’d just have to get the quantities right.”

“But your mother would still need you to make the founding stone crown her High Queen, wouldn’t she?” Destan mutters to Ruskin. “I thought that’s why she went after you in the first place.”

“She needed Ruskin because the stone rejected her without her being named heir. But it was only just managing to resist her even then,” I say. “With the extra power of Interra behind her…”

Ruskin finishes my sentence. “She might not need me to pass its trials anymore. She’s probably strong enough to overcome them alone.”

I glance over at Gawain, who looks lost and weary, as if he’s tired of being out of his depth, and wants to stop fighting the undercurrent.

“Is that all, Your Highness?” General Sunshard asks, and I realize she’s addressing Gawain. He seems to jump at the warrior speaking to him. “Is there anything else we should know about the alliance between your father and the fae queen? Why he needs so much cold iron, for instance?”

Just like her daughter, General Sunshard clearly has her mind on all possible threats. That amount of weaponry is certainly something to worry about, and yet I’d almost forgotten all about it in the wake of the founding stone news.