“Next, m matches with R. And so on. v becomes I. Ampersand becomes M h becomes V c becomes… oh, it’s a 3.”

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

P R I M V 3

“What does that mean?” Tom said.

“A number tells us it’s time to move the disk,” I said. “And also how. First we scratch out the 3 from our message. Then we move the inner disk so the letter that gave us the number—in this case, c—is now under the A.”

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

P R I M V 3

“There,” I said. “Now we have a whole new substitution. And we continue as before. t becomes L, c is now A, q is V…”

I continued, filling in the message, until I got a 2.

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

P R I M V 3 L A V V L 2

“Another number,” I said. “So we shift the inner disk again, so the d that got us the 2 is under the A.”

“Throw out the 2, and continue. k becomes G… and so on… until we’re finished.”

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

P R I M V 3 L A V V L 2 G A R I S

“Now we write it out without the numbers, and we get…”

P R I M V L A V V L G A R I S

“It didn’t work,” Sally said.

“Yes, it did,” I said. “The message is clear. It’s just not in English.”

Chapter 26

“WHAT IS IT, THEN?” TOM said.

Isaac understood. “It’s Latin. The Latin alphabet only has twenty-three letters. There’s no J, U, or W. That’s why there are so many Vs in the message. Some are actually U. Write it out,” he told me.

I did as he said.

P R I M V L A V V L G A R I S

p r i m u l a v u l g a r i s

“I still don’t know what that is,” Tom said.

“Primrose,” I said. “Primula vulgaris is the apothecary name for common primrose.”

“The flower?” Sally said. “How does that help us?”

“Perhaps,” Isaac said, “it goes with the riddle.”

Saints defend these ancient walls,

Saints we hope will save,

Visit them in hallowed halls,

And pray upon his grave.

“Pray upon his grave,” Sally said. “Oh. So you would… put flowers there? Primroses?”

“Or maybe the primroses are already there,” I said, “and we’re supposed to find them.”

“All right, so where’s ‘his’ grave? Where are the hallowed halls?”