Will looked around. "So if the blade hit this branch hard enough to do this kind of damage, maybe a tip weight came off here, Mike. Where would it have gone?"

I shook my head as I looked with him. "No idea. I just wanted to look up here to put my mind at ease. Let's push this thing as far into the tree as we can."

Will looked down. "I think the men who brought the truck are already thinking we're pretty far out from the truck. I don't want to tip over-"

"I'm not going back down until I've seen everything there is to see up here."

Will bent down as we passed under another heavy branch and into the shaded inside of the tree. I drove the basket deeper still inside the tree as the small electric motor worked against the branches. It was darker than I expected. The sun was blocked by the higher branches. My eyes adjusted slowly and I looked at every twig. Karl looked above us for any sign that other branches had been involved but weren't visible from the ground.

Karl said, "I'm not seeing much. You?"

"Not yet." I pushed against the tree. I couldn't force the basket any deeper into the tree. Karl reached up and grabbed the branch directly over our heads, pulled on it to feel its strength, and pulled himself up and out of the basket. "If we're going to do this, we've got to do it right. I've got to get to the trunk. We're still five feet away."

"You'll kill yourself."

"No, I won't. These branches are strong."

He crouched on one branch while holding the other one above his head like a rope. He moved slowly to the trunk and stood up. The broken branch was directly behind and below him. He turned carefully and grabbed the two small healthy sections of the branch that were still attached to the trunk. He felt the twisted, broken turn of the branch and the small, shredded section that kept it from plummeting to the ground. He looked outward to the brown section of the branch and imagined Marine One crashing down next to the tree.

I could see the massive blade hitting the branch and tossing it aside like a plastic straw. I tried to imagine exactly where the end cap and the tip weight would have hit. I could tell Karl was wondering the same thing. He stared for several seconds considering the numerous possibilities. He hugged the trunk and stepped down to the next branch. He looked directly under where the broken branch attached to the trunk, and there it was. Something had hit the trunk and scarred it. "See this?" he asked, pointing.

I nodded.

He moved inward and looked at the mark. The light-colored mark wasn't where something had hit the trunk at all. It was a tool mark. A knife. "Somebody worked something out of the trunk here, Mike. Could have been the NTSB found a piece of metal embedded in the trunk here and worked it out."

My heart was pounding. "Tip weight?"

Karl hesitated, then said, "Could be." He touched the bark and found a small flap next to the blade mark.

"We'd better measure the impact point and mark it on our diagram. Check the depth too. Take a picture. Maybe it will help our reconstruction."

He did, then looked for anything else that could help us. Finally he said, "Let's go back down."

I couldn't. If there was one tip weight, there could be more. They had to have been stuck to the bolt in the end of the blade, or the threads. "We'll get that tip weight from the NTSB."

"No, we won't. They'll never talk about it until the docket is released, which will be years and they may not have found one. Just dug with their knife but came up empty."

"What about the branch itself?"

Karl touched the end of the branch that was still attached, where it had been exposed from the break. Nothing. He dug his finger into the stringy remains of the connection between the still living tree and the brokenness farther out. "Something…" He pulled his Leatherman out of the case on his belt and opened the needle-nose pliers. He grabbed the branch above with one hand and reached down with the pliers with the other. He found a hard point and grabbed it.

I leaned over to look, careful to brace myself. I couldn't see anything, and he found it again with the pliers. He pulled on it hard as I grabbed the camera in the bottom of the bucket and began photographing Karl and where he was pulling. It gave. He pulled it up, wrapped his left arm around the branch, and brought it up to look at it. It was a tip weight. Half a tip weight. The circular washer-shaped piece of metal, perhaps an inch and a half across, was broken completely in half. I looked closely at it in the dim light, wondering what had caused it to break. He held it where I could see it clearly and photograph it with and without the flash.

"Tip weight," I said, confirming the obvious.

He climbed back into the bucket and handed the broken tip weight to me. A frown clouded his face. "How does this help us exactly?"

"I'm not sure it does."

"Looks broken to me, Mike. Looks like it failed in fatigue somehow. Too much of a gap between it and the next one. Probably defective. We'll have to tell the NTSB about it, and Hackett."

"In due time."

"You're not going to hide it or something, are you?"

"No." I started moving the basket back out into the sunshine.

"So what's the plan?"

"I'm going to let Bradley look at it, and he can take his time. Discovery is over in our case."

"You've got to let them know about it."

"I said I would."

"Well, it looks to me like the tip weight fractured and the lost weight did what we would expect-it caused uncontrollable vibrations. It caused the crash, Mike."

I pushed the lever on the basket and drove us downward to where Marine One had hit the ground. "Maybe. And maybe not."

THE TRIAL WAS upon us. I drove to the courthouse with Rachel, Braden, and Justin, my paralegal. The back of the Volvo was full of boxes of deposition transcripts, motions, attachments, witness outlines, and pleadings, all in clearly marked three-ring binders. I never knew what I would need, so I usually took too much. We walked up to the courthouse from our reserved parking spot. The first lady had to park out front too; there was no underground or secret parking anywhere. The journalists were quite happy about that.

It was a beautiful, sunny day, and fairly warm for Annapolis that time of year. The press had been there all night. The satellite vans were everywhere. Cords and cables ran across the street and through the bushes. Some cameras were set up on tripods, others were on the shoulders of cameramen who walked around looking for something to film. We were an hour early for the motions in limine, which were to be heard at 9 AM.

As we grabbed our boxes and began putting them on our luggage carts to wheel them into the courtroom, we were surrounded by the press. Do you have any comments, Mr. Nolan? What is your theory of the case? You say in your expert reports that the NTSB was wrong, but what do you think happened?

They had been doing their homework; they had read all the expert reports that had been filed with the court and had of course published them for all the world to see. They had read the motions in limine and had their legal consultants on top of all the issues. They were ready to go. But I wasn't talking. Nor was anybody else. "Thanks for your interest. I can't talk about it. I'll be happy to talk to you after the trial is over."

"You've got to give us something, Nolan. Tell us who your witnesses are going to be. Tell us what you're going to ask the first lady. Are you going to cross-examine her? Do you think you'll win any of your motions in limine?"

I smiled and ignored the reporters. The four of us made our way through the throng. The courthouse was brand-new, but unlike many federal and state courtrooms built today, our assigned courtroom actually had windows. Real, live daylight streamed in. Many courtrooms feel like post-op rooms, but this courthouse was designed by an architect who respected the traditional colonial architecture that dominated Annapolis. It was beautiful and inspirational, and new. It made me proud to be a lawyer every time I walked in.