He sits in the airplane, inside a cloud of cigarette smoke. He opens his wallet and looks at the permit for his handgun. He was going to buy a .22 when the salesman steered him toward a .38.

Well, if you get a .22 and a burglar comes in, he's just going to laugh at you, the salesman said. But if you have a .38 nobody's going to laugh at you. Just one shot with a .38 and you're going to bring him down.

The safest way to transport the weapon, the Federal Aviation Administration told him over the phone, was to pack it, along with the ammo, inside a suitcase—which he did. The gun was purchased legally—personal protection, he told the salesman—in Hawaii.

The ammo is another matter. Hollow-points are illegal in New York. If security decides to search his bag, he could be arrested.

It'll be fine, he keeps telling himself as he exits the plane. The biggest threat these days is skyjacking. He doesn't look like a terrorist.

He stands at the carousel inside LaGuardia, keeping an eye out for his bag while covertly watching the security people from behind the reddish-brown tinted lenses of his aviator-style eyeglasses.

No one is paying attention to him—a good sign. He picks up his suitcase.

No one comes running for him.

He heads for the exit.

No one comes looking for him.

The people he passes—business travelers and those who have come to the Big Apple to enjoy a few days of Christmas shopping—don't even acknowledge his presence. No eye contact, not a nod hello, nothing.

It's like I'm invisible.

And in a way, he is. He's been invisible his whole life. He's not remarkable in any way, which gives him a distinct tactical advantage. He can blend in anywhere, and he doesn't look threatening.

And I have to stay that way. I have to appear normal at all times.

Which means staying out of his head as much as possible.

His mind is a dangerous neighborhood.

He steps outside the airport, into the bright sunshine. The air is unseasonably warm. He drops his suitcase at the curb and, sweating and out of breath, hails a cab, his thoughts turning to the five bullets packed next to his gun. The FAA also told him that changes in air pressure could damage them.

He only needs one of them to work.

The five hollow-point Smith & Wesson +P cartridges are designed for maximum stopping power—and maximum damage. When one hits soft tissue, the tip mushrooms into a lethal miniature buzz saw that spins and bounces its way through the body, shredding tissue and organs.

One shot is more than enough to ensure John Lennon's death.

A yellow cab slides up next to him. He puts his suitcase in the trunk, then gets into the back seat. He gives the driver the address for the West Side YMCA, off Central Park West. It's only nine blocks away from his true destination.

He puts on his best smile and tells the cabbie, "I'm a recording engineer."

The taxi pulls away from the curb.

"I'm working with John Lennon and Paul McCartney."

The cabbie ignores him.

He glares at the back of the man's head. If you only knew what I'm about to do, you would be paying attention to me. You wouldn't be treating me like some nowhere man.

"Nowhere Man" is a song by his favorite group of all time, the Beatles. Well, they used to be his favorite, until they broke up. And he still hasn't forgiven John Lennon for saying that the Beatles were more popular than Jesus.

That was blasphemy.

The taxi gets in line with the bumper-to-bumper traffic heading into Manhattan. Everyone is rushing to Rockefeller Center. A sixty-five-foot Norway spruce has just been delivered, and electricians are working feverishly to prepare for the annual Christmas tree-lighting ceremony, which is only a few days away.

He takes out a bag of coke. Snorts a line off his fist.

The cabbie is now watching him in the rearview mirror.

"Want some?"

The driver shakes his head and returns his attention to the road.

The coke isn't working its magic. Instead of feeling a wave of intense pleasure, he's sweating and working himself into a rage, all of it aimed at Lennon.

"But I'd plug him anyway," he mutters. "Six shots through his fat, hairy belly."

He arrives at his destination. He pays his fare, and as he steps out of the cab, he imagines police swarming him, their weapons drawn, ready to arrest him. He sees himself locked inside a jail cell for the rest of his life.

The thought brings him comfort.

Peace.

He turns back to the driver. "I'm Mark Chapman. Remember my name if you hear it again."