Warning: Spoilers for Firefly Lane season 1.

Firefly Lane is based on a 2008 novel of the same name, but how much does the Netflix show change from the book? Firefly Lane author Kristin Hannah was a co-executive producer for Netflix’s adaptation of her book and reportedly insisted on certain aspects remaining unchanged, but the show doesn’t always follow the book.

Like many other film and television adaptations, Firefly Lane deviates from its source material on lots of minor points, but there are some rather significant changes, too. Several characters were added, and others were left out, not to mention a few major life events that were inserted to add drama and intrigue to the Netflix show.

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Any future seasons of Firefly Lane can finish telling the story that season 1 started, because the final episode of season 1 ended before the book did. Without spoiling anything from the book that might be covered in season 2, here are all the major changes that Firefly Lane made to the book in season 1.

The Timeline

Roan Curtis and Ali Skovbye in Firefly Lane on Netflix

Firefly Lane skips around in time from the ‘70s through the dawn of the new millennium. This stylistic choice allows the audience to see major life events back-to-back (like an episode full of Tully’s birthdays) and the show’s format gave more runtime to its biggest stars, Katherine Heigl and Sarah Chalke, which was likely a factor in changing the timeline. But while the two actresses have incredible on-screen chemistry as Tully and Kate, the format has some downsides. At times, the overarching story of Firefly Lane is lost in major life events and ignore the days that span in between holidays, weddings, births, and tragedies. In the book, the timeline is much more linear – the book starts in the ‘70s and ends in the mid-'00s.

Kate and Johnny's Twins

Ben Lawson and Yael Yurman in Firefly Lane on Netflix

In Firefly Lane season 1, Kate’s relationship with her daughter Marah isn’t a prominent storyline, but the tension between them visibly grows. Marah feels more connected with Tully, which is like their relationship in the book. However, in the book, Marah has siblings. Kate and Johnny have twins, who are much younger than Marah. In the year 2000, Marah is 10 years old and the twins are almost 2. It’s unclear why the twins were left out of Firefly Lane, but with so much going on in season 1, adding twins would have obviously complicated the storyline further and it’s possible that they were left out simply to make more room for Tully, Kate, Johnny, and Marah as well as the new characters that were invented for the show.

Kate and Johnny’s Divorce

Johnny and Kate in Firefly Lane on Netflix

Firefly Lane season 1, episode 1, “Hello Yellow Brick Road” reveals that present-day Johnny and Kate are estranged before telling the story of how they met, fell in love, and got married. Their separation creates a lot of drama and tension, especially when Johnny and Kate get caught up in the heat of the moment before realizing their daughter, Marah, is home, but their strained relationship is a significant departure from the book. In the novel, Johnny and Kate have their problems. Kate notices marriages crumbling all around her, which triggers her insecurities, but Johnny Ryan and Kate Mularkey remain together through it all.

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Travis

Travis in Firefly Lane

Because the Netflix show added Johnny and Kate’s divorce, it also opened the door to other relationships for Kate. Travis, Kate’s PTA crush who is not in the book, is introduced in the first episode and Johnny hints that Kate may have been unfaithful to him – and that Kate’s emotional affair with Travis is what broke their marriage. Kate denies Johnny’s allegations of an affair, saying that she exchanged a few flirtatious emails and that their hands may have touched once, but that she never cheated on him. In Firefly Lane season 1, episode 7, “Total Eclipse of the Heart,” Kate and Travis begin a sexual relationship, but at that point, Johnny and Kate’s marriage was already in shambles and it was clear they were barreling toward an eventual divorce.

Max

Max Brody in Firefly Lane

Like Travis, Max was added to the Firefly Lane television show as a love interest. Tully meets Max at a bar in the first episode. Immediately, sparks begin to fly, but their intense relationship is exclusively sexual until Max opens up to Tully. Terrified that they are beginning to develop serious feelings for each other, Tully breaks up with him. Later, Tully finds out that she’s pregnant and reconnects with Max. But Max is deeply in love with Tully, which still scares Tully. After a roller coaster of events, Tully and Max’s relationship is left up in the air.

Tully’s Pregnancy

Katherine Heigl in Firefly Lane on Netflix

Since Max was an invention of the Firefly Lane show, it follows that her pregnancy was added as well. In the book, Tully expresses her conflicting feelings about motherhood, but never becomes pregnant or has kids. The show made a huge change to Tully’s life by giving her a serious relationship and subsequent pregnancy, so Firefly Lane season 2 might have some equally significant changes for Tully’s story in season 2 – including the possibility that she might still become a mother.

Kate’s Relationship With Mutt

Mutt at the party disappointed with Kate in Firefly Lane

Mutt is a character from the Firefly Lane book, but he doesn’t have the same relationship with Kate that he does in the show. In Firefly Lane season 1, Mutt and Kate have a serious romance and Mutt is head over heels for Kate, but Kate never feels the same way about Mutt. Netflix’s adaptation of Firefly Lane changed Mutt from a minor and less likable character to a sweet, adoring boyfriend for Kate. Mutt ultimately accepts that she’s in love with Johnny and they part ways.

Related: Every Song in Firefly Lane Season 1

Sean

Sean Mularkey looking pensive in Firefly Lane

Sean exists in the Firefly Lane book, but some notable changes were made to his character. First, he’s several years younger than Kate in the book, versus the Netflix show where Sean is Kate's older brother and has a much more complex relationship with her. They fight often and have an intense rivalry for much of their youth but grow closer as adults. And while Sean's sexuality is never explicitly mentioned in the book, it's implied that he's straight.

Kate’s Parents

Margie smoking a cigarette outside

In Firefly Lane’s many flashbacks, Kate sees her mom, Margie, sitting on their couch with another man. When Kate later confronts her mother about it, Margie says that she and Bud have a “mature” love. The implication is that Margie and Bud are no longer in love, which is how Margie justifies spending time with another man, even talking with him on the phone in full view of Bud. Though Margie assures Kate that she and Bud won’t ever split up, Kate is still deeply upset by her mother’s relationship with another man. While it's all but confirmed that Margie had an affair during the show, Margie was always faithful to Bud in the book.

Bud’s Death

Sarah Chalke as Kate Mularkey in Firefly Lane

Firefly Lane’s season 1 cliffhanger ending is teased throughout the entire season. In brief flashes forward, Kate and Marah are headed to a funeral, but the identity of the deceased person isn’t revealed until the ninth episode. At first, it seems like the funeral may be for Tully. While dressed in mourning garb, Marah and Kate talked about Tully as if she were missing from their lives. Later, episode 6 reveals that Tully is still alive. At the very end of the penultimate episode, Sean and Kate reminisce about their dad, Bud, and confirm that they are at his funeral. However, Bud doesn't actually die in the novel.

Firefly Lane has hit the top spot on Netflix, but it hasn’t been renewed for a second season. Since Firefly Lane season 1 doesn’t cover the full story from the book, there is plenty of inspiration left for Firefly Lane season 2 – and the showrunners have probably started planning future storylines, since season 1 ends on multiple cliffhangers. There's a lot more to the story of lifelong best friends, Kate and Tully.

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