A tall, ascetic-looking man with white hair and a neatly trimmed beard opened it. He was dressed Sat.u.r.day casual in jeans, an open-neck collared shirt, and a burgundy sweater.

"Ms. Medina?" His voice sounded hoa.r.s.e and he cleared his throat. "Alastair Innes. You'll have to forgive me, I'm just getting over a rather nasty cold. Do come in. And thanks, Fee, for looking after her."

Fiona left and Alastair indicated the only chair in his tiny windowless office next to the door. "Please have a seat."

The s.p.a.ce was cramped and made Olivia Upshaw's Smithsonian office seem palatial. The room was barely big enough for his desk, a computer, two low bookcases, and my chair.

He closed the door and sat behind his desk.

"You're a friend of Brother Kevin's," he said. "You must be visiting from the States?"

"Actually, I lived in London for many years until last summer, so it feels like I've come home rather than being here on holiday."

He sat back in his chair and tilted it as though he needed to study me from a greater distance. "I see. Nevertheless, Wakehurst is rather off the beaten path," he said in a mild voice. "One must really make an effort to get to us. You're not a conservationist or a scientist, you're a photographer. So what really brings you to see me, Ms. Medina?"

I was getting used to the third degree from Kevin's colleagues and it was only fair. Who was I and why should they talk to me?

I told him what I could as honestly as possible without mentioning Zara Remington or my visit to the Chelsea Physic Garden. Then I needed to bluff.

"You helped Kevin identify the plant that was pressed in the pages of Adam in Eden," I said. "The one he named Bacopa lewisia extinctus."

He gave me a cool stare. "Did Kevin tell you that?"

"No, but it seems logical, given what you do and that Kevin was just here visiting you."

"I see. Well, as the name implies, the plant is extinct."

"How did you identify it, then?"

"I didn't identify it per se, merely confirmed the genus. I checked our database, which is linked to the herbarium at Kew Gardens, to see if there was any information about the species, but I found nothing. So what Kevin brought me was a unique specimen, though that's not uncommon. Every year scientists still discover approximately two thousand new species of plants."

I stared at him. "Two thousand?"

"Two thousand a year. Astonishing, isn't it?"

I nodded. "So you also know about the packets of seeds that Kevin believed supposedly went missing from the White House when the British burned it?"

He nodded. "Kevin told me his theory that they were among the items Dolley Madison rescued before the British soldiers showed up."

"If someone found them, I was told it might be possible to get the seeds to germinate, even after more than two centuries."

"You'd have to know what you're doing," he said. "But it's possible. You can't just stick them in the soil and wait for something to sprout. We've already done something similar at the Seed Bank. As a matter of fact, it's one of the objectives we're focusing on now, how to awaken plants and get dormant seeds to germinate when we know nothing about them."

"How do you do that?"

"By attempting to re-create the conditions of a plant's habitat, the temperature, humidity, type of soil, that sort of thing . . . whatever it would take for the seed to germinate naturally. For example, if we know a plant comes from a tropical part of the world, we try smoke or heat to simulate the climate."

"And it works?"

"Not all the time. But, as I said, we've had great success germinating a plant grown from seeds that are more than two hundred years old. In other words, roughly the same age as the lewisia plant."

"Where did you get two-hundred-year-old seeds?" I asked. "And how do you know that's how old they are?"

He smiled. "This particular case was extremely well doc.u.mented, so we were lucky. In 1803, a Dutchman named Jan Teerlink sailed on a ship called the Henriette, which docked in Cape Town, South Africa. While he was in port, Teerlink went ash.o.r.e and visited the famous Company's Gardens, which had been planted one hundred fifty years earlier by the Dutch East India Company. Somehow Teerlink acquired seeds from that garden, which he brought back to the ship."

"He got seeds from a garden that dated back to the 1600s?"

"That's right," Alastair said. "Teerlink stored his seeds in forty paper packets, which he placed in a red leather wallet with his name embossed on it. Unfortunately for him, the British captured the Henriette. Later he was set free, but the leather wallet with the seeds ended up in the Tower of London. At some point everything was moved to the National Archives at Kew, where the wallet was discovered quite by accident during a research project in 2005."

"You grew a plant from those seeds?"

"We did. Eventually we managed to unlock what are known as the germination codes and, of the thirty-two species of seeds in the forty packets, we got three to sprout. Two of them-an Acacia and a Leucospermum-are growing in the gla.s.shouse right now, healthy as you please."

"Can anyone see them?" I asked.

"I'm afraid not. The gla.s.shouse isn't open to the public."

"Dr. Innes, I'd be very interested in seeing those plants. And I was serious about a tour of this place when I wrote you last night. I would love to take a look inside the seed vault, too."

"I see." He steepled his fingers. "What are you planning to do after you leave here, Ms. Medina?"

"I wish you would call me Sophie," I said. "You mean, am I looking for the seeds?"

"Are you looking for the seeds, Sophie?"

"I suppose I am. Kevin wanted to find them, but he died before he could finish what he started. He told me it would be an important historic discovery and he was excited about it. He should get credit for it."

He gave me a dry look. "I presume Kevin also mentioned the ma.s.sive potential financial windfall, that there would be industries and individuals who would be interested in something like this?"

"He did. But you knew Kevin. It wasn't about the money. Anything that came his way would all go to charity anyway. I know about his sister and that he was talking to pharmaceutical companies in America to find out about drug tests for her once she was diagnosed with early-onset Alzheimer's. I think finding the lewisia plant became personal for him."

"I agree. But what about you? Is your only motive making sure Kevin gets credit where credit is due?"

I flushed but I said in an even voice, "My mother is in Connecticut at the moment with my grandfather after he was found wandering around the backyard of a former neighbor who died forty years ago. He thought they were going to go shooting together. Photos, not hunting. I adore my grandfather, and I would do anything in this world if I thought he might have Alzheimer's. However much of a long shot it was."

His eyes flickered. "I lost my wife to Alzheimer's last year. It's a living h.e.l.l to watch."

"I'm so sorry."

He studied me as though he were a.s.sessing my character, my honesty, and whether he believed me. Finally he said, "Why don't you call me Alastair?"

"Thank you."

He opened a desk drawer and pulled out a thick folder. "If those seeds are found and if they are viable, I've done a bit of preliminary research and extrapolation about what it might take to get them to germinate using the map of Lewis and Clark's journey and doing some calculations about temperature back then, and climate."

"So you really think you could get something to grow if the seeds were in good enough condition?"

"I don't know. But I promised Kevin I would do my d.a.m.nedest." He stood up. "Come. I'll give you a very quick tour of the seed vault and then we can visit the Teerlink plant in the gla.s.shouse. First, though, I need to return this folder to my safe in the lab."

"Does anyone here know about Kevin and the lewisia plant?" I asked.

"One or two colleagues are aware that Kevin and I were working on a project together. But no one knew any details because it was-how shall I say it-off the grid." He opened his office door. "You can leave your coat since we'll come back here. And I think we'll skip suiting up since we won't spend much time in the vault."

"Pardon?"

"The temperature in the seed vault is minus twenty degrees Celsius. With the windchill, it's closer to minus twenty-seven. We wear arctic gear when we go in there to do work. There are all kinds of alarms and safety backups in case anything goes wrong. After ten minutes, if whoever has entered the vault doesn't come out, all h.e.l.l breaks loose."

The lab was in the other building, so Alastair gave me a quick tour of the gla.s.s-vaulted visitor area between the two wings, where we could watch researchers and scientists at work through a series of observation windows.

"I think the seeds they're handling today came from Chile," he said. "When they first arrive they're kept in isolation until we get a chance to examine them, test them to make sure they're disease-free and healthy enough to survive storage. After that, they're cleaned, processed, and dried."

He pointed out displays of maps and photographs hinting at the global connections and reach of the Seed Bank. In one corner of the atrium was a treelike sculpture that held business cards belonging to scientists and conservationists from botanic gardens, universities, and inst.i.tutions all over the world.

"Do a lot of people work here?" I asked.

"It's a good-sized operation. On the lower level where the library and seminar room are located we have fourteen bedrooms for visiting scientists. Plus we've got a number of volunteers who are restricted to nontechnical tasks, although all of them have some kind of background in science or gardening. Don't forget, we're publicly funded, so we rely on donations and volunteer help."

He opened a door that led to the other building, and I followed him into a large laboratory where white-coated men and women sat at long tables peering into microscopes or at computer screens. The faint scent of something chemical permeated the lab, and from below us came that incessant sound of an engine humming.

"What's that noise? It sounds like a motor. I've heard it almost the entire time I've been here."

"The generators. They keep the vault at the appropriate temperature at all times. This is an energy-efficient building, but it's still an expensive operation to run. When all is said and done, we're sort of a climate-controlled Noah's Ark storing seeds for posterity. This building will be rubble someday, but the vault itself was meant to last half a millennium. It's built to withstand anything, even a nuclear bomb."

"You sound like you might be expecting the apocalypse."

He gave me a wry smile as we stepped into a room just off the laboratory. "Or at least, planning for it."

"That's kind of scary."

"We live in a scary world. There are all sorts of reasons plant species could vanish. Climate change, alien invasion-I mean predators, animals and other plants, not little green men from Mars," he said, still smiling. "Then, as you mentioned, a scenario so catastrophic it would really be the end of the world as we know it."

I shuddered as he crossed the room to a row of cabinets. He bent down and opened a cabinet door, revealing a small safe. Alastair spun the combination, pulled open the door, and set his folder inside.

"How long has the Seed Bank been here?" I asked.

"The building we're in now opened in 2000, which explains our name-Millennium Seed Bank. Before that, the staff used Wakehurst Place, the mansion. It's a beautiful estate, four hundred years old. Originally the lab was Lady Price's bedroom, the seed cleaning was done in her daughter's bedroom, and the X-ray machine was in Sir Henry's bathroom. As you can see, we've come a long way from using bathrooms to do our work."

I smiled as he shut the safe and closed the cabinet door.

"Come," he said. "It's time to see the vault. Afterward, we'll drop by the gla.s.shouse."

He led me back through the lab and eventually we came to another corridor, where we stood at a railing overlooking a wall of enormous metal doors lining the back wall of the floor below. One door-the exterior entrance to the vault-stood open. A metal spiral staircase resembling something that belonged on a ship coiled downstairs.

"We shouldn't be leaving the outer door to the vault open like that," Alastair said in a low voice as we made our way down the corkscrew staircase. "It really ought to be more secure."

I glanced up at a flash of movement above our heads; someone who had been standing at the railing now was gone. We were alone again as Alastair used his badge on another keypad that let us into a large room where brightly colored plastic crates sat on a long table and in stacks on the floor.

"This is the drying room," he said. "The vault is just through here, on the other side of this room."

Yet another door where he had to use his security badge, and this time we were in an airlock. "I should have asked this earlier," he said, "but are you asthmatic?"

The question startled me. "No. Why do you ask?"

"Three hundred thousand seeds are stored inside this vault. It's very clean but inevitably there's dust."

"I'm fine. No allergies, no asthma."

"Good. Just so you know, you're about to enter the most biodiverse place on the planet. Nowhere else in the world do this many varieties of seeds exist in one s.p.a.ce." He glanced at me. "Ready?"

"I . . . yes. Ready."

He swiped his card and pulled the door open as frigid air blasted out at us. Alastair bent and picked up a small piece of wood. A doorstop.

"We'll leave the door propped open since we're only going to be here a moment." He flipped a switch and lit up the entrance to the vault. As far as I could see into the yawning darkness, on my right were long rows of metal cabinets with doors s.p.a.ced at regular intervals every few feet. On my left was a wall of narrow floor-to-ceiling shelves containing hundreds and hundreds of what looked like gla.s.s canning jars. Each jar was filled with seeds.

"This is as far as we go," Alastair was saying. "The place is huge, and frankly, it goes on ad infinitum. But at least you get the idea, though it is hard to fathom just how ma.s.sive it is in all that inky blackness. If we used all the s.p.a.ce-and we haven't yet-the entire vault is large enough to hold thirty double-decker buses."

I shivered, as much from the cold as from the creepiness of thinking about what Alastair had just said-this vast vault, a huge underground cave buried in the bucolic English countryside, was here as insurance in case the unthinkable really did happen. The complete destruction of earth, either by our own means or perhaps an alien invasion, the little green men from Mars that Alastair had joked about, with only a few intrepid souls surviving. I tried to imagine them making their way to Wakehurst, opening the vault, and beginning life again.

Alastair must have noticed that shudder because he said, "Are you all right?"

"I'm fine." My nose had already started to tingle and I could see my breath and his.

"Like I said, they've got sensors in the control room so they know someone's in here. Let's go, shall we?"

He removed the doorstop and stuck it back in the corner where he'd found it. Then he turned off the lights and we stepped outside into the airlock.

"One more place I want to show you," he said. "It's not quite as cold, and I think you'd find it interesting. Are you game?"

"Absolutely."

We walked through more silent corridors of concrete floors and whitewashed walls without running into anyone. I had the feeling we were still underground. I also had the feeling that we were moving away from the hub of activity of the rest of the Seed Bank. More doors badged open and closed behind us with a definitive clink. Here it was as quiet as a tomb.

Eventually we came to a short flight of stairs. "It's just up here," Alastair said.

I followed him. "What is this place?"

He badged open another door and propped it open with another doorstop. "The rest of the vault. We can move walls back, expand to make the refrigerated vault we were just in larger as we need more s.p.a.ce and the collection grows in size. Have a look."

The triangle of light from the open door shone partway into the enormous room. Gradually, as my eyes became accustomed to the darkness, I realized we were standing in a cavernous s.p.a.ce that seemed to go on and on forever. About fifty feet in front of us were rows of shelves stacked with boxes that seemed to reach the ceiling.

"What are those boxes for?" I asked.

"For now this is a good place to store anything we don't need in the main facility. Come over here and have a look at this wall."

We walked over to the shelving and he pointed out the wall behind it. "You can see how it's a type of modular construction. We just b.u.mp it out as we need the s.p.a.ce."

Neither of us heard the noise, a sc.r.a.ping sound, until it was too late and the triangle of light began to disappear as the door started to swing shut. We both ran for the door.