Seven years ago on the morning of September 11th, the phone rang for Alice Hoagland.
"Mom, this is Mark Bingham," said the young man, giving his mother his full name. "I'm on a flight from Newark to San Francisco. There are three guys who've taken over the plane, and they say they have a bomb.
"You believe me, don't you, Mom?"
Bingham, a 31-year-old entrepreneur with a zest for rugby and adventure, was on United Flight 93, headed back home to a friend's wedding in California.
The phone went quiet. And then Alice Hoagland said what would be among her last words to her only son: "Yes, Mark, I believe you."
Sunday, Hoagland arrived here, at Guantanamo Bay, Cuba, to finally see the man who orchestrated that murderous day of horror and carnage. Khalid Sheikh Mohammed is facing charges of murdering 2,973 people, and Hoagland is among a group of victims and families chosen by a lottery to watch his military commission hearings.
"You'd have to be a very bloodthirsty and inhuman person to hatch such a plot," Hoagland, a warm and open woman, told ABC News. "That's one reason why I'm glad I'm going to sit in the same room with Khalid Sheikh Mohammed and sort of take measure of that man, because he claims responsibility. He takes credit, if you will, for hatching that ugly plot."
The deadly impact of that plot shattered Hoagland's life.
"I still wake up nights startled by the fact that my only child is dead," she said. "They've taken the most precious thing out of my life. I'll never be the same."
Hoagland has made another life, as an advocate for the victims' families and for reform. In a way, she has moved on.
But she also remains very much back in that day, when she got that phone call from Mark. She and other victims' family members have listened to the cockpit tapes, and she describes them in graphic detail -- the shouting and thunderous noises as Bingham and other passengers stormed the cockpit, the wind screaming over the plane's wings as it hurled to the ground.
And when she talks about that day, she relieves it.
After Mark's call to her the morning of Sept. 11th was cut off, Hoagland, desperate for information, began frantically calling "everybody we could think of." The FBI, United Airlines, the police.
She turned on the television, and she saw the horrific scene of the World Trade Center in flames. And then she saw the second plane hit.
"It was… it was the most horrible…," she said, her voice trailing off, as she remembers what went through her mind. "I thought, 'Is that Mark's plane?' And it turned out that it wasn't.
"Then we heard about the Pentagon being hit. Was that Mark's plane? And then they started announcing what flight numbers they were. United Airlines 175 into the South Tower. American Airlines Flight 11 into the North Tower. American flight 77 into the Pentagon.
And then her sister-in-law frantically called her to the television: "Guys, they just mentioned Flight 93."This is what Hoagland saw on the television screen: "They showed a panorama of the scene there outside of Shanksville, Pennsylvania, with hemlock trees afire and a huge, gaping hole covered over with some debris and emergency crews standing around, already."
"Seeing that," she said, "I knew that, of course, there were no survivors."
On that day, she had never heard of Khalid Sheikh Mohammed, the self-confessed mastermind of the plot that took her son and 2,972 others. Monday, she will be in the same courtroom, watching.
On the flight down to Guantanamo Sunday, she told me she feels "dread" at seeing him.
But she also said she wishes KSM and the other terrorists could see more of the victims' families, "and to look into the faces of all the thousands of people whose lives they changed so bitterly that day."
She is only one.