"I'm investigating a suspicious death, and the information might be material."

"Alllll right, buddy."

"h.e.l.lo?"

Peter Zell's townhouse, 14 Matthew Street Extension, is a new building, cheap construction, with just four small rooms: living room and kitchen on the first floor, bedroom and bathroom upstairs. I linger on the threshold, recalling the relevant text from Criminal Investigation advising me to work slowly, divide the house into a grid, take each quadrant in its turn. Then the thought of the Farley and Leonard-my reflexive reliance on it-reminds me of Naomi Eddes: it sounds like you're quoting from a textbook or something. I shake that off, run a hand over my mustache, and step inside.

"Okay, Mr. Zell," I say to the empty house. "Let's have a look."

The first quadrant gives me precious little to work with. A thin beige carpet, an old coffee table with ring-shaped stains. A small but serviceable flat-screen TV, wires snaking up from a DVD player, a vase of chrysanthemums that turn out, on close inspection, to be made of fabric and wire.

Most of Zell's bookshelf s.p.a.ce is given over to his professional interests: math, advanced math, ratios and probabilities, a thick history of actuarial accounting, binders from the Bureau of Labor Statistics and the National Inst.i.tutes of Health. Then he's got one shelf where all the personal stuff sits, as if quarantined, all the nerdy sci-fi and fantasy stuff, Battlestar Galactica: The Complete Series, vintage D&D rule-books, a book on the mythological and philosophical underpinnings of Star Wars. A small armada of s.p.a.ces.h.i.+p miniatures is suspended from wires in the doorway to the kitchen, and I duck to avoid them.

In the pantry are nine boxes of cereal, carefully alphabetized: Alpha-Bits, Cap'n Crunch, Cheerios, and so on. There is one empty slot in the neat row, like a missing tooth between the Frosted Flakes and the Golden Grahams, and my mind automatically fills in the missing box: Fruity Pebbles. A stray candy-pink grain confirms my hypothesis.

"I like you, Peter Zell," I say, carefully closing the pantry door. "You, I like."

Also in the kitchen, in an otherwise empty drawer beside the sink, is a pad of plain white paper, with writing on the top sheet that says, Dear Sophia.

My heart catches on a beat, and I breathe and I pick up the pad, flip it over, rifle through the pages, but that's all there is, one sheet of paper with the two words, Dear Sophia. The handwriting is precise, careful, and you can tell, you can feel that this was not a casual note Zell was writing, but an important doc.u.ment, or was meant to be.

I tell myself to remain calm, because it could after all be nothing, though my mind is blazing with it, thinking that whether it's the start of an aborted suicide note or not, it is definitely something.

I tuck the pad into the pocket of my blazer, walk up the stairs, thinking, who is Sophia?

The bedroom is like the living room, sterile and unornamented, the bed haphazardly made. A single framed print hangs over the bed, a signed still from the original Planet of the Apes film. In the closet hang three suits, all in dull shades of brown, and two threadbare brown belts. In a small, chipped-wood night table beside the bed, in the second drawer down, is a s...o...b..x, wrapped tightly in duct tape, with the number 12.375 written on the outside in the same precise handwriting.

"Twelve point three seven five," I murmur. And then, "What is this?"

I tuck the s...o...b..x box under my arm and stand up, take a look at the one photograph in the room: it's a small print in a cheap frame, a school picture of a boy, maybe ten or eleven years old, thin yellow flyaway hair, gawky grin. I tug it from the frame and flip it over, find careful handwriting on the back. Kyle, February 10. Last year. Before.

I use the CB to raise Trish McConnell.

"Hey," I say, "it's me. Were you able to locate the victim's family?"

"Yes, indeed."

Zell's mother is dead, as it turns out, buried here in Concord, up at Blossom Hill. The father is living at Pleasant View Retirement, suffering the opening phases of dementia. The person to whom McConnell delivered the bad news is Peter's older sister, who works as a midwife at a private clinic near Concord Hospital. Married, one child, a son. Her name is Sophia.

On my way out, I stop again on the threshold of Peter Zell's house, awkwardly carrying the s...o...b..x and the photograph and the white notepad, feeling the weight of the case and balancing it against an ancient memory: a policeman standing in the doorway of my childhood home on Rockland Road, hatless and somber, calling, "Anybody home?" into the morning darkness.

Me standing at the top of the stairs, in a Red Sox jersey, or it might have been a pajama top, thinking my sister is probably still asleep, hoping so anyway. I've already got a pretty good idea what the policeman's there to say.

"Let me guess, Detective," says Denny Dotseth, "We've got another 10-54S."

"Not a new one, actually. I wanted to touch base with you about Peter Zell."

I'm easing the Impala down Broadway, hands at ten and two. There's a New Hamps.h.i.+re state trooper parked at Broadway and Stone, engine on, the blue lights slowly rotating on the roof, a machine gun clutched in his hand. I nod slightly, raise two fingers off the wheel, and he nods back.

"Who's Peter Zell?" says Dotseth.

"The man from this morning, sir."

"Oh, right. Hey, you hear they named the big day? When we'll know where she comes down, I mean. April 9."

"Yep. I heard."

Dotseth, like McGully, likes to keep up-to-date on every unfolding detail of our global catastrophe. At the last suicide scene, not Zell's but the one before that, he talked excitedly for ten minutes about the war on the Horn of Africa, the Ethiopian army swarming into Eritrea to avenge ancient grievances in the time remaining.

"I thought it made sense to present you with what I've learned so far," I say. "I know your impression from this morning, but I think this might be a homicide, I really do."

Dotseth murmurs, "Is that a fact?" and I take that as a go-ahead, give him my sense of the case thus far: The incident at Merrimack Life and Fire, on Halloween. The red pickup truck, burning vegetable oil, that took the victim away the night he died. My hunch on the belt from Belknap and Rose.

All of this the a.s.sistant AG receives with a toneless "interesting," and then he sighs and says, "What about a note?"

"Uh, no. No note, sir."

I decide not to tell him about Dear Sophia, because I feel fairly certain that whatever that is, it is not an aborted suicide note-but Dotseth will think it was, he'll say, "There you go, young man, you're barking up the wrong tree." Which he pretty clearly thinks I'm doing anyway.

"You got some straws to grasp at there," is what he says. "You're not going to refer this case to Fenton, are you?"

"I am, actually. I already did. Why?"

There's a pause, and then a low chuckle. "Oh, no reason."

"What?"

"Hey, listen, kid. If you really think you can build a case, of course I'll take a look. But don't forget the context. People are killing themselves right and left, you know? For someone like the fella you're describing, someone without a lot of friends, with no real support system, there's a powerful social incentive to join the herd."

I keep my mouth shut, keep driving, but this line of reasoning I do not like. He did it because everyone else is doing it? It's like Dotseth is accusing the victim of something: cowardice, perhaps, or mere faddishness, some color of weakness. Which, if in fact Peter Zell was murdered, murdered and dragged into a McDonald's and left in that bathroom like meat, only adds insult to injury.

"I'll tell you what," says Dotseth genially. "We'll call it an attempted murder."

"Sorry, sir?"

"It's a suicide, but you're attempting to make it a murder. Have a great day, Detective."

Driving down School Street there's an old-time-style ice-cream parlor on the south side of the road, right where you pa.s.s the YMCA, and today it looks like they're doing a pretty brisk business, snow or no snow, dairy prices or no dairy prices. There's a nice-looking young couple, early thirties maybe, they've just stepped outside with their colorful cones. The woman gives me a small tentative friendly-policeman wave, and I wave back, but the man looks at me dead-eyed and unsmiling.

People in the main are simply muddling along. Go to work, sit at your desk, hope the company is still around come Monday. Go to the store, push the cart, hope there's some food on the shelves today. Meet your sweetheart at lunch hour for ice cream. Okay, sure, some people have chosen to kill themselves, and some people have chosen to go Bucket List, some people are scrambling around for drugs or "wandering around with their d.i.c.ks out," as McGully likes to say.

But a lot of the Bucket Listers have returned, disappointed, and a lot of newly minted criminals and wild pleasure-seekers have found themselves in jail, waiting in terrified solitude for October.

So, yeah, there are differences in behavior, but they are on the margins. The main difference, from a law-enforcement perspective, is more atmospheric, harder to define. I would characterize the mood, here in town, as that of the child who isn't in trouble yet, but knows he's going to be. He's up in his room, waiting, "Just wait till your father gets home." He's sullen and snappish, he's on edge. Confused, sad, trembling against the knowledge of what's coming next, and right on the edge of violence, not angry but anxious in a way that can easily shade into anger.

That's Concord. I can't speak to the mood in the rest of the world, but that's pretty much it around here.

I'm back at my desk on School Street, back in Adult Crimes, and I'm carefully cutting away the duct tape that holds the lid of the s...o...b..x, and for the second time since I met her I hear the voice of Naomi Eddes-standing there with her arms crossed, staring at me, so what are you looking for, anyway?

"This," I say, when I have the lid off the box and I'm staring inside. "This is what I'm looking for."

Peter Zell's s...o...b..x contains hundreds of newspaper articles, magazine pages, and items printed from the Internet, all relating to Maia and its impending impact with Earth. I lift the first of the articles off the top of the stack. It's from April 2 of last year, an a.s.sociated Press squib about the Palomar Observatory at Caltech and the unusual but almost certainly harmless object the scientists there had spotted, which had been added to the Potentially Hazardous Asteroid list at the Minor Planet Center. The author concludes the article by dryly noting that "whatever its size or composition, this mysterious new object's odds of impacting Earth are estimated at 0.000047 percent, meaning there is a one in 2,128,000 chance." Zell, I note, has carefully circled both numbers.

The next item in the s...o...b..x is a Thomson Reuters piece from two days later, headlined "Newly Discovered s.p.a.ce Object Largest in Decades," but the article itself is rather mundane, a single paragraph, no quotes. It estimates the size of the object-in those early days still being referred to by its astronomical designation of 2011GV1,-as "among the largest spotted by astronomers in some decades, possibly as large as three kilometers in diameter." Zell has circled that estimate, too, faintly, in pencil.

I keep reading, fascinated by this grim time capsule, reliving the recent past from Peter Zell's perspective. In each article, he has circled or underlined numbers: the steadily increasing estimates of Maia's size, its angle in the sky, its right ascension and declination, its odds of impact as they inch higher, week by week, month by month. He's put neat boxes around each dollar amount and percentage of stock-value loss in an early-July Financial Times survey of the desperate emergency actions of the Fed, the European Central Bank, and the International Monetary Fund. He has, too, articles on the political side: legislative wrangling, emergency laws, bureaucratic shuffles at the Justice Department, the refunding of the FDIC.

I am picturing Zell, late at night, every night, at his cheap kitchen table, eating cereal, his gla.s.ses resting at his elbow, marking up these clippings and printouts with his mechanical pencil, considering every unfolding detail of the calamity.

I pluck out a Scientific American piece dated September 3, asking in big bold letters, "How Could We Not Have Known?" The short answer, which I already know, which everyone knows by now, is that 2011GV1's highly unusual elliptical orbit brings it close enough to be visible from Earth only once every seventy-five years, and seventy-five years ago we weren't looking, we had no program in place to spot and track Near-Earth Asteroids. Zell has circled "75" each time it appears; he's circled 1 in 265 million, the now-moot odds of such an object existing; he's circled 6.5 kilometers, which by then had been determined to be Maia's true diameter.

The rest of the Scientific American article gets complicated: astrophysics, perihelions and aphelions, orbital averaging and values of elongation. My head is spinning reading all of this, my eyes hurt, but Zell has clearly read every word, thickly annotated every page of it, made dizzying calculations in the margins, with arrows leading to and from the circled statistics and amounts and astronomical values.

Carefully I place the cover back on the box, look out the window.

I place my long flat palms on the top of the box, stare again at the number on the side of the box, written firmly, in black marker: 12.375.

I'm feeling it again-something-I don't know what. But something.

"May I speak to Sophia Littlejohn? This is Detective Henry Palace of the Concord Police Department."

There's a pause, and then a woman's voice, polite but unsettled. "This is she. But I think you folks have got your wires crossed. I already spoke to someone. This is-you're calling about my brother, right? They called earlier today. My husband and I both spoke to the officer."

"Yes, ma'am. I know."

I'm on the landline, at headquarters. I'm judging Sophia Littlejohn, picturing her, painting myself a picture from what I know, and from the tone of her voice: alert, professional, compa.s.sionate. "Officer McConnell gave you the unfortunate news. And I'm really sorry to be bothering you again. As I said, I'm a detective, and I just have a few questions."

As I'm talking I'm becoming aware of an unpleasant gagging noise; over there on the other side of the room is McGully, his black Boston Bruins scarf twisted up over his head into a comedy noose, going "erk-erk." I turn away, hunch over my chair, holding the receiver close to my ear.

"I appreciate your sympathy, Detective," Zell's sister is saying. "But I honestly don't know what else I can tell you. Peter killed himself. It's awful. We weren't that close."

First Gompers. Then Naomi Eddes. And now the guy's own sister. Peter Zell certainly had a lot of people in his life with whom he wasn't that close.

"Ma'am, I need to ask if there's any reason your brother would have been writing you a letter. A note of some kind, addressed to you?"

On the other end of the phone, a long silence. "No," says Sophia Littlejohn finally. "No. I have no idea."

I let that hang there for a moment, listen to her breathe, and then I say, "Are you sure you don't know?"

"Yes. I am. I'm sure. Officer, I'm sorry, I don't really have time to talk right now."

I'm leaning all the way forward in my chair. The radiator makes a metallic chugging noise from its corner. "What about tomorrow?"

"Tomorrow?"

"Yes. I'm sorry, but it really is very important that we speak."

"Okay," she says, after another pause. "Sure. Can you come to my home in the morning?"

"I can."

"Very early? Seven forty-five?"

"Anytime is fine. Seven forty-five is fine. Thank you."

There's a pause, and I look at the phone, wondering if she's hung up, or if the landlines are now having trouble, too. McGully tousles my hair on his way out, bowling bag swinging from his other hand.

"I loved him," says Sophia Littlejohn suddenly, hushed but forceful. "He was my little brother. I loved him so much."

"I'm sure you did, ma'am."

I get the address, and I hang up, and I sit for a second staring out the window, where the slush and sleet just keep on coming down.

"Hey. Hey, Palace?"

Detective Andreas is slumped in his chair on the far side of the room, tucked away in darkness. I hadn't even known he was in the room.

"How you doing, Henry?" His voice is toneless, empty.

"Fine. How about you?" I'm thinking about that glistening pause, that lingering moment, wis.h.i.+ng I could have been inside Sophia Littlejohn's head as she cycled through all the reasons her brother might have had for writing Dear Sophia on a piece of paper.

"I'm fine," Andreas says. "I'm fine."

He looks at me, smiles tightly, and I think the conversation is over, but it's not. "I gotta say, man," Andreas murmurs, shaking his head, looking over at me. "I don't know how you do it."

"How I do what?"

But he's just looking at me, not saying anything else, and from where I'm sitting across the room it looks like there are tears in his eyes, big pools of standing water. I look away, back out the window, just no idea what to say to the guy. No idea whatsoever.