A second history librarian showed them to a rare book room, gave them gloves, and allowed them to examine the volumes in the Las Casas collection for about three hours, going from one volume to the next. All of the volumes were bound or rebound in old leather. Some were hand-copied Latin or Spanish in archaic handwriting, some were incunabula—works printed before 1500—a few in medieval Gothic script with hand-painted illumination. Most were religious works in Latin. There were commentaries on the Bible, collected sermons, multiple copies of breviaries. There was a copy of the Corpus Aristotelicum. There were also Spanish volumes written or copied in a hand that was clearly the same as the writing on the letter that had been hidden in the Mayan codex. Whenever they saw one, it excited them, but none was what they had come so far to find. The treasure they searched for would consist of Mayan pictures and glyphs, not Spanish text.

At the end of the day, just before it was time for visitors to leave the library, the desk librarian made an announcement that readers should return books. The Fargos gave theirs up immediately, went to the desk to retrieve Remi’s bag, and left. As they emerged onto the patio outside the building, Remi whispered, “Have you seen those two men before?”

Sam stopped, apparently to look around him at the medieval Spanish architecture but took a moment to find the men she meant. They were already walking off in another direction. “I saw a couple of men earlier on the Calle Gondomar, but I can’t tell if those are the same ones. What did they do?”

“I could feel them staring at us.”

Sam smiled. “You could feel them staring at you, more likely. You should be used to that.”

That evening, Sam and Remi began their exploration of the city’s nightlife with the Plaza Mayor, right outside their hotel. They sampled the coffee in the Continental, then went for pinchos, the favorite local iteration of tapas, at Restaurante Los Zagales. They were made of morcilla sausages, red onion, and pork rind, all wrapped into a roll.

Each day, Sam and Remi walked from the Zenit Imperial Hotel and returned to the History Library to examine the next group of five-hundred-year-old books.

After the library closed that afternoon, Sam and Remi returned to their hotel for a nap, then got up at ten to begin their evening of exploring. That night they tried Taberna Pradera, known for the fresh calamari cracker in its own ink. The following night, they tried Fortuna 25, which served a free-range chicken stuffed with mussels and algae. Another night, it was Taberna del Zurdo. They drank Rueda, Ribera del Duero, and other fine Spanish red wines, moving from place to place as though each evening were a celebration.