"When she asked me for help, my heart broke," Brad Meltzer tells PEOPLE of his high school history teacher
Credit: Ryan Kuttler

Almost 30 years after graduating from high school, bestselling author Brad Meltzer set out to find a way to thank his beloved 11th grade history teacher, Ellen Sherman.

Little did he know that dedicating his 2013 book, History Decoded: The 10 Greatest Conspiracies of All Time, to his former teacher would set off a chain of events that would ultimately save her life.

When word of the dedication got back the now retired 71-year-old, she reached out to thank her former student. After a few email exchanges Sherman – or Mrs. Sherman, as Meltzer still calls her – shared some sad news: She was in desperate need of a kidney transplant, but she couldn’t find a matching donor.

“She said, ‘I’m sick. I’m dying. I need a kidney,’ ” Meltzer tells PEOPLE. “When she asked me for help, my heart broke I couldn’t possibly not help. This woman changed my life.”

The author, who also hosts the series Lost History on the History Channel, turned to his Facebook following of almost 100,000 people in hopes of finding a match for his former teacher.

“Maybe I’m insane, or maybe this is going to be the best Spreading Kindness story of all time,” he wrote in a Facebook post in November 2013.

Dozens of potential donors volunteered to be tested but more than a year and a half later, Sherman still hadn’t found a match.

After Meltzer, 45, put out a second call for help he received a Facebook message from Amy Waggoner, a 36-year-old graphic designer in Chantilly, Virginia, who said she had reached out to Sherman but never heard back. Worried Waggoner may have “slipped through the cracks,” Meltzer passed the note on to his former teacher.

“I just had a feeling about it,” he says.

A couple weeks later an email from Sherman confirmed his intuition: Waggoner was a match. She donated her kidney to Sherman last week.

Meltzer visited the two women in the hospital shortly after the successful 10-hour surgery, and Sherman was already feeling better.

“She had been saying for years that she had a brain fog, that she couldn’t really think straight [because of the disease]. And when I asked her how she was feeling she just looked at me in that moment and said, ‘My brain fog’s gone.’ ”

Meltzer says he never imagined his Facebook posts would make such a big impact. At the time he simply thought, “I’m going to try past the point where everyone else would give up.”

“Sometimes you just have to listen to the universe,” he adds. “You can say it’s God, you can say it’s whatever you believe in but this was just one of those things that felt like it was meant to be.”

Of course, Sherman may never have found her happy ending if she hadn’t asked for help in the first place – which makes Meltzer’s book dedication all the more fitting: “For my history teacher Ellen Sherman, who taught me the power of asking the right questions.”

To find out more about becoming a kidney donor, visit floodsisters.org.