As they ate brie-and-mushroom sandwiches, Dan drew skulls and Roman numerals on a napkin.
"Twelve, five, fourteen," he said. "Those are the missing numbers."
Amy didn't bother checking his math. He never messed up on number problems.
"Maybe it's an address and an arrondissement," she said.
Nellie wiped off her iPod. "Wouldn't the address have changed in two hundred years?"
Amy got a hollow feeling in her gut. Nellie was probably right. Paris might not have had the arrondissement system when Franklin lived here. And street addresses definitely would've changed -- in which case Franklin's clue was no good anymore.
Would Grace have sent them on a search that couldn't be finished?
Why not? a resentful voice said inside of her.
Grace didn't care enough to tell you about the quest in person. If Dan had died in that rail pit, it would've been Grace's fault.
No, she decided. That wasn't true. Grace must've had a reason. The numbers must refer to something else. Amy could only think of one way to find out -- the same thing she did whenever she had an unsolvable problem. "We need to find a library."
Nellie talked to the waiter in French, and he seemed to understand what they wanted.
"Pas de problè me," he said.
He drew a map on a fresh napkin and scribbled the name of a Métro station: é cole Militaire.
"We have to hurry," Nellie said. "He says the library closes at six."
Half an hour later, soggy and still smelling like the Catacombs, they arrived at the American Library in Paris.
"Perfect," Amy said. The old building had black metal security bars over the doorway, but they were open. Peering inside, Amy saw stacks of books and plenty of comfortable places to read.
"Why should these guys help us?" Dan asked. "I mean, we don't have a library card or anything."
But Amy was already climbing the steps. For the first time in days, she felt absolutely confident. This was her world. She knew what to do.
The librarians came to their aid like soldiers responding to a battle cry. Amy told them she was researching Benjamin Franklin, and within minutes Amy, Dan, and Nellie were sitting at a table in a conference room, examining reproductions of Franklin documents -- some so rare, the librarians told her, the only copies existed in Paris.
"Yeah, here's a rare grocery list," Dan muttered. "Wow."
He was about to toss it aside when Amy grabbed his wrist.
"Dan, you never know what's important. Back then there weren't many stores. If you wanted to buy something, you had to send the merchant an order and have your stuff shipped. What did Franklin buy?"
Dan sighed. '"Please to send the following: 3 --
Treatise on Cyder Making by Cave;
2 -- Nelson on the Government of Children,
8 vol., by Dodsley; 1 Qty. -- Iron Solute;
Letters from a Russian Officer -- '"
"Hold it," Amy said. '"Iron Solute.' Where have I heard that before?"
"It was on that other list," Dan said without hesitation, "in one of the letters we saw in Philadelphia."
Amy frowned. "But iron solute isn't a book. This whole list is books except for that."
"What's iron solute, anyway?" Dan asked.
"Oh, guys, I know this!" Nellie chimed in. She held up her hands and closed her eyes like she was remembering the answer for a test. "It's like a chemical solution, right?
They use it for metalworking and printing and a bunch of other stuff."
Amy stared at her. "How did you know that?"
"Hey, I took chemistry last semester. I remember 'cause the professor was talking about, like, how they make high-end cooking equipment. Franklin probably used iron solute for his ink when he was a printer."
"That's great," Dan muttered. "Except for the fact that it's completely unimportant]
Now can we get back to the magic box coordinates?"
Amy still felt something nagging in the back of her head, like she was missing a connection, but she rifled through the rest of the papers. Finally, she unfolded a huge yellowing document that turned out to be an old-fashioned map of Paris. Her eyes widened.
"This is it." Amy put her finger proudly over a spot on the map. "A church. St-Pierre de Montmartre. That's where we need to go."
"How can you be sure?" Nellie asked.
"The numbers form a grid, see?" She pointed to the margins. "This is an old surveyor's map by a couple of French scientists, Compte de Buffon and Thomas-Francois D'Alibard. I remember reading about them. They were the first to test Franklin's lightning rod theories. After they proved the rods worked, King Louis XVI ordered them to draw up a plan to outfit all the major buildings in Paris. That church was the fourteenth installation, at coordinates five by twelve. Franklin would've known about the work. He was really proud of how the French took to his ideas. That has to be it. I'll bet you a box of French chocolate we'll find an entrance to the Catacombs at the church."
Dan looked doubtful. Outside, the rain was really coming down. Thunder shook the windows of the library. "What if the Kabras get there first?"
"We have to make sure that doesn't happen," Amy said. "Come on!"
Dan felt like one of the Catacomb skulls -- hollowed out inside.
He was determined not to show it. He was embarrassed enough that he'd cried on the train platform. But he kept reaching for his backpack and it wasn't there. He couldn't stop thinking about his parents' picture, whisked away and lost in the Métro tunnels.
Maybe it had been ripped to shreds, or maybe his parents would be smiling in the darkness forever with no company but the rats. All he'd wanted to do was make them proud. Now he didn't know if his parents would ever forgive him.
The rain was still coming down. Thunder boomed across the sky. Every few minutes a flash of lightning would illuminate the Paris skyline.
If Dan had been in a better mood, he would've wanted to explore Montmartre. It looked like a cool neighborhood. The whole area was one big hill, topped with a massive white-domed church that glowed in the rain.
"That's where we're going?" Dan asked.
Amy shook her head. "That's the Sacré-Coeur Basilica. The smaller church, St-Pierre, is just below it. You can't see it from here."
"Two churches right together?"
"Why wouldn't Franklin choose the big fancy one?"
Amy shrugged. "Wasn't his style. He liked simple architecture. He would've thought it amusing to choose a small plain church in the shadow of a big fancy one."
That didn't make much sense to Dan, but he was too wet and tired to argue. They hiked up the narrow streets, passing nightclubs with music blaring and neon signs that gleamed against the wet pavement.
"I used to have a nightlife," Nellie sighed.
As they climbed toward the top of the hill, Amy told them what she knew about the neighborhood -- how famous artists used to live here like Picasso, Vincent van Gogh, and Salvador Dali.
Nellie pulled her raincoat tighter. "My mom told me another story -- why it's called Montmartre, the Hill of the Martyr. She said Saint Denis was beheaded at the summit, right where we're going."
That didn't sound like a very good omen. Dan wondered if they still kept the head in the church, and whether saints' heads really had haloes.
A few minutes later they stood in a muddy graveyard, looking up at the dark silhouette of St-Pierre de Montmartre. The church was probably taller than it seemed, but with the white basilica towering on the hill behind it, St-Pierre looked short. It was made of gray stone slabs. A single square bell tower rose from the left-hand side, topped with a lightning rod and cross. Dan thought the building looked angry and resentful. If churches could frown, this one would.
"How do we know where to look?" he asked.
"Inside the sanctuary?" Nellie asked hopefully. "At least we'd be out of the rain."
Thunder rolled across the rooftops. Lightning flashed, and in that second, Dan saw something.
"There," he said. "That tombstone."
"Dan," Amy complained, "this is no time for your collection!"
But he ran to a marble marker. If he hadn't been a tombstone admirer, he never would've noticed it. There were no dates. No name. At first, Dan thought the figure carved at the top was an angel, but the shape was wrong. It was weathered and worn, but he could still tell-
"Entwined serpents," Amy gasped. "The Lucian crest. And there -- "
She knelt and traced an arrow carved at the base of the marker -- an arrow pointing down into the earth.
Amy and Dan looked at each other and nodded.
"Oh, you're kidding," Nellie said. "You're not really going to -- "
"Dig up a grave," Dan said.
They found a toolshed around the side of the church. They borrowed a shovel, a couple of gardening spades, and a flashlight that actually worked. Soon they were back at the graveside, digging in the mud. The rain made it hard going. In no time, they were completely filthy. It reminded Dan of the good old days when Amy and he were young. They used to have mud battles and their au pair would shriek in horror and make them spend the evening in a bubble bath, getting cleaned up.
Dan didn't think Nellie was going to make them a bubble bath tonight.
Slowly, the hole got deeper. It kept filling with water, but finally Dan's shovel struck stone. He scraped away the mud and found a marble slab about four feet long by three feet wide.
"Too small for a coffin," Amy said.
"Unless it's for a kid," Dan said. "I could fit in there."
"Don't say that!"
Dan wiped the mud off his face, which just made it muddier. "Only one way to find out." He worked the spade under the edge of the slab until he found a crack and then started to pry. "I need help."
Amy joined him. Nellie got the shovel into the crack and together they heaved the slab aside. Beneath was a square hole, but it wasn't a grave. Stairs led down, into the darkness of the Catacombs.
As soon as they reached the bottom, Dan swept the flashlight around the room. It was a square chamber hewn from limestone, with a tunnel exiting to the left and the right.
There were no stacks of bones, but the walls were painted with faded murals. In the center was an ornately carved stone pedestal about three feet high. On the top sat a porcelain vase.
"Don't touch it!" Amy said. "It might be booby-trapped."
Dan edged closer to the vase. "It's decorated with little Franklins."
He could make out Ben holding a kite in a storm, Ben in a fur cap, Ben waving a cane over the ocean like he was doing some kind of magic trick.
"It's a souvenir vase," Amy said. "The kind they made in the 1700s to celebrate Franklin's arrival in Paris."
"Twenty bucks says something's inside," Dan offered.
"No bet," Amy said.
"Guys," Nellie said. "Look at this."
She was standing at the back wall. Dan came over and shone the light on the mural.
The colors were faded, but Dan could make out four figures: two men and two women, dressed in old-fashioned clothes -- even older than from Franklin's time, like from the Middle Ages or the Renaissance or something.