The Rule of Four

by Ian Caldwell

  Finally, we discuss the conversation we had with Stein in the Rare Books Room, which Paul says the police took down in full. As he talks about Bill, about how agitated Stein was at the library, about the friend he’s lost, Paul gives little sign of emotion. He still hasn’t recovered from the shock.

  “Tom,” he says finally, when we’re back in our bedroom, “I need a favor.”

  “Of course,” I say. “Name it.”

  “I need you to come with me.”

  I hesitate. “Where?”

  “The art museum.”

  He’s changing into a dry set of clothes.

  “Now? Why?”

  Paul rubs at his forehead, working out an ache. “I’ll explain on the way.”

  When we return to the common room, Charlie looks at us like we’ve lost our minds. “At this hour?” he asks. “The museum’s closed.”

  “I know what I’m doing,” Paul says, already making for the hallway.

  Charlie gives me a heavy look, but says nothing as I follow Paul out the door.

  The art museum sits like an old Mediterranean palace across the courtyard from Dod. From the front, where we entered a few hours earlier, it’s just a stumpy modern building with a Picasso sculpture on the front lawn that looks like a glorified birdbath. When you approach from the side, though, the newer elements give way to older ones, pretty windows in little Romanesque arches, and red roof-tiles that peek out beneath tonight’s canopy of snow. Under different circumstances, the view from here would be charming. Under different circumstances, it might be a picture Katie would take.

  “What are we doing?” I ask.

  Paul is trudging a path before me in his old workman’s boots.

  “I found what Richard thought was in the diary,” he says.

  It sounds like the middle of a thought whose beginning he’s kept to himself.

  “The blueprint?”

  He shakes his head. “I’ll show you when we get inside.”

  I’m walking in his footsteps now to keep the snow out of my pant legs. My eyes keep returning to his boots. Paul worked at the museum loading docks our freshman summer, moving incoming and outgoing exhibits onto trucks. The boots were a necessity then, but tonight they leave dirty tracks in the moon-white of the courtyard. He looks like a boy in men’s shoes.

  We arrive at a door by the west face of the museum. Beside it is a tiny keypad. Paul dials in his docent’s password and waits to see if it works. He used to give tours at the art museum, but finally had to take a job in the slide library because the docents weren’t paid.

  To my surprise, the door opens with a beep and a whisper of a click. I’m so used to the medieval-sounding bolts of the dorm doors, I almost don’t hear it. He leads me into a small antechamber, a security room supervised by a guard behind a plate-glass window, and suddenly I feel trapped. After signing a visitation form on a clipboard, though, and pressing our university IDs against the glass, we’re cleared to enter the docent’s library beyond the next door.

  “That’s it?” I say, expecting more of a shakedown at this hour.

  Paul points to a video camera on the wall, but says nothing.

  The docent’s library is unimpressive—a few shelves of art history books donated by other guides to help prepare for tours—but Paul continues toward an elevator around the corner. A large sign posted on the sliding metal doors says FACULTY, STAFF, AND SECURITY ONLY. STUDENTS AND DOCENTS NOT PERMITTED WITHOUT ESCORT. The words students and docents have both been underlined in red.

  Paul is looking somewhere else. He pulls a key ring from his pocket and plugs one of them into a slot in the wall. When he turns it to the right, the metal doors slide open.

  “Where’d you get that?”

  He leads me into the elevator, then presses a button. “My job,” he says.

  The slide library gives him access to archival rooms in the museum. He is so careful about his work that he has earned almost everyone’s trust.

  “Where are we going?” I say.

  “Up to the image room. Where Vincent keeps some of his slide carousels.”

  The elevator discharges us on the main floor of the museum. Paul guides me across it, ignoring the paintings he’s pointed out to me a dozen times before—the vast Rubens with its dark-browed Jupiter, the unfinished Death of Socrates with the old philosopher reaching for his cup of hemlock. Only when we pass the paintings Curry brought for the trustees’ exhibit do Paul’s eyes wander.

  We reach the door to the slide library, and he produces the keys again. One of them shifts quietly into place, and we enter the darkness.

  “Over here,” he says, pointing toward an aisle of shelves lined with dusty boxes. Each box contains a slide carousel. Behind another locked door, in a large room I’ve seen only once, rests much of the university’s collection of art slides.

  Paul finds the set of boxes he’s been searching for, then lifts one from the stack and places it on the shelf before him. A note taped to the side, written in a sloppy hand, says MAPS: ROME. He takes the top off and carries the box to the small open space near the entrance. From another shelf he produces a slide projector, which he plugs into a wall socket near the ground. Finally, with the flick of a switch, a blurry image appears on the opposite wall. Paul adjusts the focus until it sharpens into position.

  “Okay,” I say. “Now tell me what we’re doing here.”

  “What if Richard was right?” he says. “What if Vincent stole the diary from him thirty years ago?”

  “He probably did. What does it matter now?”

  Paul brings me up to speed. “Imagine you’re in Vincent’s position. Richard keeps telling you the diary is the only way to understand the Hypnerotomachia. You think he’s blowing smoke, just a college kid with an art history degree. Then someone else shows up. Another scholar.”

  Paul says it with a certain respect. I gather he’s referring to my father.

  “Suddenly you’re the odd man out. Both of them say the diary is the answer. But you’ve painted yourself into a corner. You’ve told Richard the diary is useless, that the portmaster was a charlatan. And more than anything, you hate being wrong. What do you do now?”

  Paul is trying to convince me of a possibility I’ve never had trouble accepting: that Vincent Taft is a thief.

  “I get it,” I say. “Go on.”

  “So you somehow steal the diary. But you can’t make anything of it, because you’ve been looking at the Hypnerotomachia all wrong. Without the ciphered messages from Francesco, you don’t know what to do with the diary. What then?”

  “I don’t know.”

  “You’re not going to throw it away,” he says, ignoring me, “just because you don’t understand it.”

  I nod my agreement.

  “So you keep it. Somewhere safe. Maybe the lockbox in your office.”

  “Or in your house.”

  “Right. Then, years later, this kid comes along, and he and his friend start making progress on the Hypnerotomachia. More than you expected. In fact, more than you made in your prime. He starts finding the messages from Francesco.”

  “You start thinking the diary might be useful after all.”

  “Exactly.”

  “And you don’t tell the kid about it, because then he would know you stole it.”

  “But,” Paul continues, arriving at his point, “say one day someone found it.”

  “Bill.”

  Paul nods. “He was always in Vincent’s office, at Vincent’s house, helping with all the little projects Vincent made him do. And he knew what the diary meant. If he’d found it, he wouldn’t have just put it back.”

  “He would’ve brought it to you.”

  “Right. And we turned around and showed it to Richard. Then Richard confronted Vincent at the lecture.”

  I’m skeptical. “But wouldn’t Taft have realized it was gone before that?”

  “Of course. He had to know Bill took it. But what do you think his reaction was when he realize
d Richard knew about it too? The first thing on his mind would’ve been to go find Bill.”

  Now I understand. “You think he went to Stein’s office after the lecture.”

  “Was Vincent at the reception?”

  I take it as a rhetorical question until I remember Paul wasn’t there; he’d already left to find Stein.

  “Not that I saw.”

  “There’s a hallway connecting Dickinson and the auditorium,” he says. “Vincent didn’t even have to leave the building to get there.”

  Paul lets it sink in. The possibility drifts through my thoughts clumsily, tethered to a thousand other details. “You really think Taft killed him?” I ask. A strange silhouette forms from the shadows of the room, Epp Lang burying a dog beneath a tree.

  Paul stares at the black contours projected on the wall. “I think he’s capable of it.”

  “Out of anger?”

  “I don’t know.” But he already seems to have been through all of the scenarios in his mind. “Listen,” he says, “when I was waiting for Bill at the Institute, I started reading the diary more carefully, looking for every mention of Francesco.”

  He flips it open and inside the front cover is a page of notes he’s made on Institute stationery.

  “I found the entry where the portmaster records the set of directions the thief copied from Francesco’s papers. Genovese says they were written on an empty scrap of paper, and must’ve formed some kind of nautical route, something about the path Francesco’s ship took. The portmaster tried to figure out where the cargo must’ve come from by working backward from Genoa.”

  When Paul unfolds the stationery, I can see a pattern of arrows drawn near a compass.

  “These are the directions. They’re in Latin. They say: Four south, ten east, two north, six west. Then they say De Stadio.”

  “What’s De Stadio?”

  Paul smiles. “I think that’s the key. The portmaster took it to his cousin, who told him De Stadio was the scale that went with the directions. It can be translated ‘Of Stadia,’ meaning the directions are measured in stadia.”

  “I don’t get it.”

  “The stadium is a unit of measurement from the ancient world, based on the length of a footrace in the Greek Olympics. That’s where we get our modern word. About six hundred feet is one stadium, so there are between eight and ten stadia in a mile.”

  “So four south means four stadia south.”

  “Then ten east, two north, and six west. It’s all four directions. Does it remind you of something?”

  It does: in his final riddle, Colonna referred to what he called a Rule of Four, a device that would lead readers to his secret crypt. But we gave up on finding it when the text itself failed to produce anything remotely geographical.

  “You think that’s it? Those four directions?”

  Paul nods. “But the portmaster was looking for something on a much bigger scale, a voyage of hundreds and hundreds of miles. If Francesco’s directions are in stadia, then the ship couldn’t have originated in France or the Netherlands. It must’ve started its trip about half a mile southeast of Genoa. The portmaster knew that couldn’t be right.”

  I can see Paul’s giddiness, thinking he’s done the portmaster one better. “You’re saying the directions were meant for something else.”

  He hardly pauses. “De Stadio doesn’t just have to mean ‘Of Stadia.’ De could also mean ‘from.’ ”

  He looks at me expectantly, but the beauty of this new translation is lost on me.

  “Maybe the measurements aren’t just of stadia, or measured in those units,” he says. “Maybe they’re also taken from a stadium. A stadium could be the starting point. De Stadio could have a double meaning—you follow the directions from a physical stadium building, in stadia units.”

  The map of Rome projected on the wall is coming into focus. The city is littered with ancient arenas. Colonna would’ve known it better than any city in the world.

  “It solves the scale problem the portmaster had,” Paul continues. “You can’t measure the distance between countries in a few stadia. But you can measure the distance across a city that way. Pliny says the circumference of the Roman city walls in A.D. 75 was about thirteen miles. The entire city was maybe twenty-five or thirty stadia across.”

  “You think that will lead us to the crypt?” I ask.

  “Francesco talks about building where no one can see. He doesn’t want anyone to know what’s inside it. This may be the only way to find the location.”

  Months of speculation return to me. We spent many nights wondering why Colonna would build his crypt out in the Roman forests, hidden from his family and friends, but Paul and I never agreed about our conclusions.

  “What if the crypt is more than we thought?” he says. “What if the location is the secret?”

  “Then what’s inside it?” I say, reviving the question.

  Paul’s demeanor changes to frustration. “I don’t know, Tom. I still haven’t figured it out.”

  “I’m just saying, don’t you think Colonna would’ve—”

  “Told us what was in the crypt? Of course. But the entire second half of the book depends on the last cipher, and I can’t solve it. Not alone. So this diary is it. Okay?”

  I back off.

  “So all we have to do,” Paul goes on, “is look at a few of these maps. We start at the major stadium areas—the Coliseum, the Circus Maximus, and so on—and move four stadia south, ten east, two north, and six west. If any of those locations is in what would’ve been a forest in Colonna’s time, we mark it.”

  “Let’s look,” I say.

  Paul presses the Advance button, shifting through a series of maps made in the fifteenth and sixteenth centuries. They have the quality of architectural caricatures, buildings drawn out of proportion with their surroundings, crowded up against each other until the spaces in between are impossible to judge.

  “How are we going to measure distances on those?” I ask.

  He answers me by pumping the hand control several more times. After three or four more Renaissance maps, a modern one appears. The city looks more like the one I remember from travel books my father gave me before our trip to the Vatican. The Aurelian Wall on the north, east, and south and the Tiber River on the west create the profile of an old woman’s head facing the rest of Italy. The church of San Lorenzo, where Colonna had the two men killed, hovers like a fly just beyond the arch of the old woman’s nose.

  “This one has the right scale on it,” Paul says, pointing to the measurements in the upper-left corner. Eight stadia are marked along a single line, labeled ANCIENT ROMAN MILE.

  He walks toward the image on the wall and places his hand beside the scale. From the base of his palm to the tip of his middle finger, he covers the full eight stadia.

  “Let’s start with the Coliseum.” He kneels on the floor and places his hand near a dark oval in the middle of the map, near the old woman’s cheek. “Four south,” he says, moving a palm-length down, “and ten east.” He moves one full hand-length across, then adds half an index finger. “Then two north and six west.”

  When he finishes, he’s pointing to a spot labeled M. CELIUS on the map.

  “You think that’s where it is?”

  “Not there,” he says, deflated. Pointing to a dark circle on the map just southwest of his finishing point, he says, “Right over here is a church. San Stefano Rotondo.” He shifts his finger northeast. “This is another one, Santi Quattro Coronati. And here”—he moves the finger southeast—“is Saint John Lateran, where the popes lived until the fourteenth century. If Francesco had built his crypt here, he would’ve done it within a quarter mile of three different churches. No way.”

  He begins again. “The Circus Flaminius,” he says. “This map is old. I think Gatti placed it closer to here.” He moves his finger closer to the river, then repeats the directions.

  “Good or bad?” I say, staring at the location, somewhere atop the Palatine
Hill.

  He frowns. “Bad. This is almost right in the middle of San Teodoro.”

  “Another church?”

  He nods.

  “You’re sure Colonna wouldn’t have built it near a church?”

  He looks at me as if I’ve forgotten the cardinal rule. “Every message says he’s terrified of being caught by the zealots. The ‘men of God.’ How do you interpret that?”

  Losing patience, he tries two other possibilities—the Circus of Hadrian and the old Circus of Nero, over which the Vatican was built—but in both cases, the rectangle of twenty-two stadia lands him almost in the middle of the Tiber River.

  “There’s a stadium in every corner of this map,” I tell him. “Why don’t we think about where the crypt could be, then work backward to see if there’s a stadium near it?”

  He mulls it over. “I’d have to check some of my other atlases at Ivy.”

  “We can come back here tomorrow.”

  Paul, whose supply of optimism is thinning, eyes the map a moment longer, then nods. Colonna has beat him again. Even the spying portmaster was outwitted.

  “What now?” I ask.

  He buttons his coat, turning off the projector. “I want to check Bill’s desk in the library downstairs.” He returns the slide machine to its shelf, trying to leave everything where he found it.

  “Why?”

  “To see if anything else from the diary is there. Richard insists there was a blueprint folded inside it.”

  He opens the door and holds it for me, checking the room before locking it up.

  “You have a key for the library?”

  He shakes his head. “Bill told me the punch code for the stairwell.”