In her first on-air interview, Tennessee girl Elizabeth Thomas sat down to discuss what happened before, during, and after the 38 days her former teacher, Tad Cummins, reportedly abducted her.

Elizabeth was just 15 when she disappeared from her Columbia, Tennessee, home in March 2017. Her disappearance sparked an AMBER Alert and a nationwide hunt after authorities determined a former health sciences teacher, Tad Cummins, 52, was responsible for taking her. In April 2017, authorities found the pair living in a bare shack without running water or electricity, deep inside a wooded area in northern California.

While Cummins sits behind bars facing both state and federal charges, Elizabeth spoke with “20/20” correspondent Eva Pilgrim and explained how a grown man pursued a romantic relationship with her before taking her across state lines, even dying her hair and altering his own appearance to avoid detection.

According to Elizabeth, after flirting with her and kissing her while she was a student at the Culleoka Unit School in Maury County, Cummins demanded that she leave the state with him and start a new life. Elizabeth said Cummins had a gun in his car and threatened to harm her and her family unless she left with him.

Further, Elizabeth explained that prior to attending public school, she was home schooled and had never had a boyfriend before she met Tad. She was shocked at the advances he made, but also confused since she had no idea how to handle it.

“It was fourth period or fourth block,” Elizabeth explained, recalling the first time Cummins made an advance toward her. “I can’t remember the conversation and then next thing I know he said, ‘You’d look pretty nice naked.'”

Elizabeth said she knew things were going too far when Cummings “grabbed” her face and kissed her while the pair were inside his classroom. She said she was scared to tell anyone because she didn’t like bringing that kind of attention to herself.

“I was scared. Like, I don’t want to tell my parents that a grown man kissed me. I don’t want to tell friends that a grown man kissed me. I don’t like the spotlight being on me.”

In attention to Elizabeth’s version of events, “20/20” interviews those closest to both Elizabeth and Cummins’, including,

• Jill Cummins, Tad’s wife who has filed for divorce
• Ashlee Conner and Erica Osborne, Tad’s daughters
• Elizabeth’s father, Anthony Thomas
• Elizabeth’s brother and sister, Josh and Sarah Thomas
• Jason Whatley, attorney for the Thomas family
• District Attorney Brent Cooper
• Griffin Barry, the man who turned in a tip that led to Cummins’ arrest

The full interview with Elizabeth airs on “20/20” on Friday, September 21 at 11 p.m. ET on ABC<span “>.

[Feature Photo: Elizabeth Thomas via ABC, “20/20”]