The story takes place across several decades, as Tully Hart (played by Ali Skovbye as a teenager and Katherine Heigl as an adult) and Kate Mularkey (played by Roan Curtis as a teenager and Sarah Chalke as an adult) become lifelong friends after meeting in 1974. The series flips back and forth between scenes in the '70s, '80s, and 2003 to tell the full story of their epic friendship. And as the show hops around in different decades, the music plays a key role in grounding the viewer in each timeline.
The same is true in the book, with music being one of the ways author Kristin Hannah set the tone and mood of each decade. "What I particularly loved about writing this novel was the memories it evoked," Hannah wrote on her website. "Fads, fashion, products, songs, novels, and news stories — this book contains all of that." Her website features a playlist of all the songs and artists that Kate and Tully listen to in the novel, several of which also ended up in the show.
Warning: There are spoilers for Firefly Lane season 1 ahead.