“That’s where the rest of the history matters,” Isaac said. “The treaty was a humiliation for Charles. He hated the Covenant, yet not only was he forced to sign it, he was then made to sit through constant lectures about the evils of his ways, and of his father in particular. By the time Cromwell came for him, Charles loathed not only the Covenant, but all of Scotland as well.

“When the Commonwealth finally fell in 1660, and Charles returned to his throne, the Scots expected our king to honor the Covenant. Instead, His Majesty rejected it, and took revenge on those who’d humiliated him. That might have ended things, but Charles appointed governors over Scotland who hate its people as much as he does.

“As you might imagine, this has not gone well. There’s been unrest up north for years. I promise you, open rebellion is coming. I’m surprised we haven’t seen it already.”

“So the threats against the king…,” Tom began.

“Are almost certainly from Covenanters,” Isaac finished. “They’d gladly assassinate him if they could.”

I thought of the Scotsmen who’d been waiting outside the palace gates. Another English slight! one had said, outraged. And the other… he’d followed us into the Banqueting House.

Were they part of the threat?

I had no way of knowing. And there was something about all this that didn’t add up. “If it’s Covenanters,” I said, “and they’re after the king, why murder the servant girls? Simon, I can just understand—if they think I’m going to help His Majesty, and Simon is with me… but why a pair of maids? It doesn’t make sense.”

“To kill a king,” Isaac said, “you have to get close to him. Charles spends his days inside Whitehall, surrounded by armed guards. They can’t just raise an army to attack the palace.

“But if they infiltrated the palace, put an assassin inside—”

“And if the servants spotted something wrong!” Sally said. “Servants see everything. They’d need to be silenced.”

It all fit. The threat against the king, the riddle’s broken oath, the maids murdered at Whitehall. I thought again of the Scotsmen at the gate—and wondered if this was what Walsingham thought, too. I’d have to tell him what we’d discovered.

“So,” I said. “Covenanters are trying to kill the king. And the Templars are trying to help us stop them.”

“I still don’t see why we have to go through all these riddles,” Tom said.

Isaac placed the second puzzle on the table. “Let’s try solving it and find out.”

We all huddled over the letter.

Saints defend these ancient walls,

Saints we hope will save,

Visit them in hallowed halls,

And pray upon his grave.

la ruota dell’italiano

B s m v & h c t c q q t d k d & l x

“ ‘Saints defend these ancient walls,’ ” Tom repeated. “Which walls? London’s?”

“Or someplace in London,” I said. “Whitehall, maybe? If the king is under threat?”

“ ‘Saints we hope will save,’ ” Sally quoted. “Does that mean… patron saints?”