MAHONEY CALLED IN our new position as we followed the GPS off the Beltway and onto Eisenhower Avenue. It was getting dark, but the roads were still crowded with commuters. I wondered vaguely when nine-to-five had become an anachronism.

A mile and a half up Eisenhower, we came to a row of identical four-story townhouses fronting the street.

A break in the road marked the entrance with a sign welcoming visitors to Avalon at Cameron Court.

The GPS led us through the mini-maze of the compound inside. It was one of those upscale developments, "communities," with their own everything. Rents here were as high as thirty-five hundred a month, according to Mahoney and his laptop.

"You know, my aunt lives in a place like this, down in Vero Beach, Florida. They have a two-pet maximum, but she's got four identical little dogs. Just walks them two at a time."

I sort of listened, until we came onto Nicholson's block. "Hey, Ned. See that?" A dark blue sedan was just pulling out of a driveway about fifty yards ahead. "Is that Nicholson's building?"

Mahoney sat up and closed the laptop. "Could be. Let's find out."

The other car started up the block, heading right toward us. It had DC plates. Two men in front, two passengers in back who were harder to see.

As we passed, I looked in, and for just a second I locked eyes with Tony Nicholson.

AS SOON AS my siren came on, the dark blue sedan took off up the block and then spun around the corner. I had no idea who these guys were – mob, guns for hire, or what – but the way they tore out of there told me Nicholson and his girlfriend were in some serious trouble.

Ned was already on the phone. "This is Mahoney. I have command of the target, Nicholson. We're in pursuit of a blue, Pontiac G6, DC plates."

We came around another corner, and I saw them stopped at the compound's exit.

"One for the good guys!" Ned said, and pumped a fist. There was a solid stream of traffic on Eisenhower blocking them in, and for maybe a second, I thought we might get through this cleanly.

Then the Pontiac 's doors opened on both sides and two men came out – firing!

A bullet pierced my windshield with a dull popping sound before Ned or I could get out. I threw open my door and rolled onto the street. Mahoney also got out the driver's side and stayed low.

From where I was, in a gully, I could only see the sedan's driver. He looked military to me, tall, with a blond buzz cut – and still firing. I didn't shoot back, didn't dare.

The problem was the traffic stopped behind him. There wasn't a safe shot I could take. He seemed to figure that out, and broke for the nearest building.

As he passed the large Avalon sign fronting the complex, I fired off a fast, controlled double tap. Two shells kicked over my shoulder. The blond man went down with the second one.

But we weren't out of this yet, not by a long shot. Mahoney was up and firing. I could see the other man now, down in the street. He had a wet hole in the leg of his pants, but he got up again.

"Drop your weapon!" Mahoney shouted, as the man began to hobble away.

I came around to cover from a second angle, just as the guy raised a.45 at Mahoney.

Both our shots got off before his. He spasmed twice when they hit, and still managed to pull the trigger one more time. His shot nearly clipped Ned, who dropped and fired back. The last bullet caught the guy in the shoulder.

The shooter was alive when we got to him, wide-eyed and tremoring, his finger still on the trigger. Ned stepped on his wrist and pulled the.45 out of his hand.

"Hang in there," I told him. "Ambulance is on its way."

He was in bad shape, though. A wound in his stomach was pumping blood, too much and too fast. While Mahoney ran to Nicholson and the woman, I pulled off my jacket and pressed it to the wound.

"Who do you work for?" I asked.

I wasn't sure if he could hear me. He didn't look scared, but his eyes were like saucers. When he tried to swallow, foamy blood came through his lips. My jacket was already soaked.

"Tell me!" I finally shouted at him. "Who sent you here?"

The gunman's breath hitched, and his grip went tight on my arm – just before everything went lax. He died without saying a word that might help us understand, well, anything about what was happening.

OUR TWO DEAD soon became three, when Charlotte Nicholson, her face blue, the body still warm, turned up in the Pontiac 's trunk.

Tony Nicholson and his presumed girlfriend, Mara Kelly, were both mute except to say that they hadn't done anything wrong and they had no idea who the dead men were. That's as much as we got before the FBI took them into custody.

By now, the response team had swelled to three Bureau cars, Alexandria police, EMTs, and the local sheriff's department. As soon as I could, I called Bree to check in.

That's when I realized that my phone had been off for hours – ever since the sweep at the private club out in Culpeper. When I turned it on, there were three voice mails waiting – all from Bree.

Right away I got nervous.

I listened to the first message. "Hey, it's me. Listen, the doctors are concerned about Nana's kidney function. They say her fluid levels aren't what they should be. There's no prognosis yet, but you should give me a call. Love you."

I turned toward my car now and started walking, not at all sure I wanted to hear the second message.

"Alex, it's Bree. I tried the Bureau, but nobody seems to know where you are. I don't have Ned's cell. I'm not sure what else to do. Nana isn't good. I hope you get this soon."

I was running, but the third message nearly stopped me cold on the spot.

"Alex, where are you? I hate to leave this on your phone, but… Nana's gone into a coma. I'm going back in now, so you won't be able to reach me anymore. Get here as soon as you can."

THE FUNCTION BEING held at One Observatory Circle tonight was relatively informal, a Maryland crab boil for several midlevel staffers and their families. That meant jackets with no ties – until the vice president went to shirtsleeves just before dinner and his male guests followed suit.

Agent Cormorant, however, kept his jacket on. It was specially tailored to conceal a.357 SIG Sauer pistol holstered under his right arm, and though the event was distinctly low-threat, it was not in Cormorant's professional DNA to take anything for granted, especially not these days.

Secret Service had been covering the sprawling Victorian residence since 1972. The Rockefellers had never moved in, but the Mondales, Bushes, Quayles, Gores, and Cheneys had all lived here before the Tillmans. Every corner of the place was well documented, literally. Cormorant knew the house better than his own two-bedroom condo on M.

So when he needed a private word with the vice president, it was second nature to access the library through a back sitting room, to avoid being seen coming or going by any of the guests.

Tillman poured himself a scotch rocks and waited by the mantel while Cormorant closed and latched doors at both ends of the room.

"What is it that can't wait, Dan?" Tillman asked.

"I should tell you right now, sir, that I'm about to step way out of line here," Cormorant said.

Tillman sipped his drink. "That's something new. The warning, I mean."

The two men were friends, as much as men in their positions could be. Someday they'd share fishing trips and holidays, but for now, it was Mr. Vice President and Agent Cormorant – protectee and protector.

"Sir, I think it's time you brought the president in on Zeus. Specifically the fact that someone connected to the White House or the Cabinet might be a killer."