No one said a word.

'And I think we all know what the answer is,' he went on. 'Now finding where the doc lives is no big problem. It's been in the newspapers enough, and if you find her, you find Benton. But you?'

He pointed at Lucy.

'You're the challenge, because Carrie'd been locked up for several years by the time you moved here. And now you're moving to Philly, and Janet's left here alone. And to be honest, I don't like that worth a damn, either.'

'Neither of you is listed in the phone book, right?' I asked.

'No way,' Janet said, and she was listlessly picking at her salad.

'What if someone called this building and asked for either of you?'

'They're not supposed to give out info like that,' Janet said.

'Not supposed to,' Marino said sardonically. 'Yeah, I'm sure this joint's got state-of-the-art security. Must be all kinds of high profile people living here, huh?'

'We can't sit around worrying about this all of the time,' Lucy said, and she was getting angry. 'Can't we talk about something else?'

'Let's talk about the Warrenton fire,' I said.

'Let's do.'

'I'll be packing in the other room,' Janet said appropriately, since she was FBI and not involved in this case.

I watched her disappear into a bedroom, and then I said, 'There were some unusual and disturbing findings during the autopsy. The victim was murdered. She was dead before the fire started, which certainly points at arson. Have we made any further headway on how the fire might have been set?'

'Only through algebra,' Lucy said. 'The only hope here is fire modeling, since there's no physical evidence that points at arson, only circumstantial evidence. I've spent a lot of time fooling around with Fire Simulator on my computer, and the predictions keep coming back to the same thing.'

'What the hell is Fire Simulator?' Marino wanted to know.

'One of the routines in FPEtool, the software we use for fire modeling,' Lucy explained patiently. 'For example, we'll assume that flashover is reached at six hundred degrees Celsius - or one thousand, one hundred and twelve degrees Fahrenheit. So we plug in the data we know, such as the vent opening, area of surface, energy available from the fuel, fire virtual point of origin, room lining materials, wall materials, and so on and so on. And at the end of the day, we should get good predictions as to the suspect, or the fire in question. And guess what? No matter how many algorithms, procedures, or computer programs you try with this one, the answer's always the same. There's no logical explanation for how a fire this fast and hot could have started in the master bathroom.'

'And we're absolutely sure it did,' I said.

'Oh yeah,' Lucy said. 'As you probably know, that bathroom was a relatively modern addition built out from the master bedroom. And if you look at the marble walls, the cathedral ceiling we recovered, you can piece together this really narrow, sharply defined V pattern, with the apex pointing somewhere in the middle of the floor, most likely where the rug was, meaning the fire developed really fast and hot in that one spot.'

'Let's talk about this famous rug,' Marino said. 'You light it, and what kind of fire do we get?'

'A lazy flame,' Lucy answered. 'Maybe two feet tall.'

'Well, that didn't do it,' I said.

'And what's also really telling,' she went on, 'is the destruction to the roof directly above. Now we're talking flames at least eight feet high above the fire's origin, with the temperature reaching about eighteen hundred degrees for the glass in the skylight to melt. About eighty-eight percent of all arsons are up from the floor, in other words the radiant heat flux…'

'What the hell's radiant flux?' Marino wanted to know.

'Radiant heat is in the form of an electromagnetic wave, and is emitted from a flame almost equally in all directions, three hundred and sixty degrees. Following me so far?'

'Okay,' I said.

'A flame also emits heat in the form of hot gases, which weigh less than air, so up they go,' Lucy, the physicist, went on. 'A convective transfer of heat, in other words. And in the early stages of the fire, most of the heat transfer is convective. It moves up from its point of origin. In this case, the floor. But after the fire was going for a while and hot gas-smoke layers formed, the dominant form of heat transfer became radiant. It was at this stage that I think the shower door fatigued and fell on top of the body.'

'And what about the body?' I asked. 'Where would that have been during all this?'

Lucy grabbed a legal pad off the top of a box and clicked open a pen. She drew the outline of a room with a tub and shower and, in the middle of the floor, a tall narrow fire that was impinging upon the ceiling.

'If the fire was energetic enough to project flames to the ceiling, then we're talking about a high radiant flux. The body was going to be severely damaged unless there was a barrier between it and the fire. Something that absorbed radiant heat and energy - the tub and shower door - which would have protected areas of the body. I also think the body was at least some small distance from the point of origin. We could be talking feet, maybe a yard or two.'

'I don't see any other way it could have happened,' I agreed. 'Clearly something protected much of it.'

'Right.'

'How the hell do you set off a torch like that without some sort of accelerant?' Marino asked.

'All we can hope is that something turns up in the labs,' my niece said. 'You know, since the fuel load can't account for the observed fire pattern, then something was added or modified, indicating arson.'

'And you guys are working on a financial audit,' Marino said to her.

'Naturally almost all of Sparkes's records burned up in the fire. But his financial people and accountant have been pretty helpful, to give the guy credit. So far there's no indication that money was a problem.'

I was relieved to hear it. Everything I knew about this case so far argued against Kenneth Sparkes being anything but a victim. But this was not an opinion that was shared by most, I felt sure.

'Lucy,' I said as she finished her gyro pita. 'I think we're all in agreement that the MO of this crime is distinctive.'

'Definitely.'

'Let's just suppose,' I went on, 'for the sake of argument, that something similar has happened before, somewhere else. That Warrenton is simply part of a pattern of fires used to disguise homicides that are being committed by the same individual.'

'It's certainly possible,' Lucy said. 'Anything is.'

'Can we do a search?' I then asked. 'Is there any database that might connect similar MOs in fires?'

She got up and threw food containers in a large trash bag in the kitchen.

'You want to, we can,' she said. 'With the Arson Incident System, or AXIS.'

I was well acquainted with it and the new supersonic ATF wide area computer network called ESA, which was an acronym for Enterprise System Architecture, the result of ATF being mandated by Congress to create a national arson and explosive repository. Two hundred and twenty sites were hooked up to ESA, and any agent, no matter where he was, could access the central database, could pipe himself into AXIS with his laptop as long as he had a modem or a secure cellular line. This included my niece.

She led us back to her tiny bedroom, which was now depressingly bare save for cobwebs in corners and dust balls on the scuffed hardwood floor. The box springs were empty, the mattress still made with wrinkled peach sheets and upended against a wall, and rolled up in a corner was the colorful silk rug that I had given her for her last birthday. Empty dresser drawers were stacked on the floor. Her office was a Panasonic laptop on top of a cardboard box. The portable computer was in a shark-gray steel and magnesium case that met military specifications for being ruggedized, meaning it was vapor-proof and dust-proof and everything-proof and supposedly could be dropped and run over by a Humvee.