The September 11 anniversary has special meaning to a Henderson family.
Danny Lee had been in Boston for work and was flying home that day in 2001 so he could see the birth of his child. His flight was one of the planes to crash into the World Trade Center.
Danny's wife Kelly gave birth to their daughter Allison two days later.
"It's like the happiest day of your life and the worst day of your life in one day," Kellie Lee said.
That duality was reflected in the dozens of cards Kellie Lee received in the following weeks. Many of them were simultaneously condolences and congratulations.
"Both of my daughters have grown up to be wonderful, talented people and it just hurts [that] he's missing this," Kellie Lee said. "He missed them grow up. He just would've been so proud."
Allison learned about her father and 9/11 as she got older.
"I learned that he traveled around the world a lot, so I definitely want to do that because he did it," she said.
Danny Lee was a roadie for many famous musical artists, including the Backstreet Boys and Aerosmith.
For the 15th anniversary of his death, Allison and her friends have created a dance video tribute to the man she never got to meet.
The other Lee daughter, Amanda, was a toddler when Danny died. She describes the anniversary every year as surreal.
"It's kind of happy because my sister's birthday is two days later," Amanda Lee said. "It's weird."
The Lees have been to the 9/11 museum and memorial in New York City, but Sunday they went to Danny's favorite restaurant.
They ordered his favorite food and just talked about the man that was taken from all of them far too soon.