Delilah Mcphee is having a rough junior year. She and her mom, Grace, have moved to a new town after Grace's divorce, and Delilah is starting at a new school. Delilah escapes her reality through reading, and she's obsessed with a fairy- tale book called Between the Lines. Delilah turns the pages of the book to various tableaus featuring the Fairy-tale Characters, Prince Oliver, the evil Rapskullio, Princess Seraphima, and Mermaids, but she pauses when a new word appears on the page: "help" ("Another Chapter").

In the school library, Allie Mcandrews, the resident mean girl, is with her minions: Ryan, Janice, and Martin. Ryan is Allie's not-so-bright boyfriend, Martin is her social media manager, and Janice is her right- hand gal. Ms. Winx, the librarian, introduces Delilah to Jules, a loner and outsider like Delilah, in hopes they'll become friends. The introduction doesn't go well.

Back at home, Delilah receives an eviction notice from a Process Server. She immediately calls her dad, who is supposed to be paying their rent. Grace intercepts the call and begins to fight with her ex, and Delilah escapes to the roof with her book to be alone. Suddenly, Prince Oliver speaks to her ("Between the Lines - Part 1").

Delilah struggles to comprehend that a character from a book is speaking to her ("Between The Lines - Part 2"). Delilah and Prince Oliver discover they have a lot in common: they are both dissatisfied with their current circumstances ("Between the Lines - Part 3"). They agree to meet the next day - on the only page where Prince Oliver is alone ("After Between The Lines").

When the book closes, the Fairy-Tale Characters are off-duty ("Happily Ever After Hours - Part 1 and Part 2"). Frump, a human cursed to be a dog, plays the piano while Queen Maureen, Rapskullio, Lady-in-Waiting, Troll, the mermaid Ondine, and Pixie lament their storybook roles. Princess Seraphima, who is none too bright, doesn't understand the difference between the Fairy-Tale Characters' book roles and their real personalities.

The next day at school, Allie, her minions, and the Students contemplate their lives ("Inner Thoughts"). Delilah and Prince Oliver continue to bond, and Delilah fantasizes about their conversations ("When I'm Talkin' To Oliver"). Back in the library, Ms. Winx also has a book that speaks to her, in the form of Mr. Darcy ("Mr. Darcy And Me").

After an incident with Allie, Delilah and Jules finally become friends. Back at home, Delilah and Grace have a fight.

In chemistry class, Mrs. Brown assigns Delilah and Jules as chemistry partners. Allie and her minions pick on Delilah ("Crazy Chemistry") and take the fairy-tale book. Delilah tries to get her book back from Allie and in the struggle, accidentally hits her.

Back in the fairy-tale book, Rapskullio is happily frolicking amongst his Butterflies ("Butterflies") when Prince Oliver requests that he use his magic canvas and paint a portrait of Delilah so she can enter the fairy tale. In the real world, Delilah is on the roof. She's been suspended from school, is worried about Grace's reaction, and wishes she could change her story ("A Whole New Story").

Suddenly, Delilah falls into the fairy-tale world, right onto page 59! Everyone is delighted at Delilah's arrival ("Best Day Ever"). Prince Oliver proposes to Delilah, but the Mermaids interrupt, encouraging Delilah to fix her own problems ("Do It For You"). Delilah determines that she can't leave everyone in the real world behind ("Do It For You - Tag") and sets off to find Rapskullio, who is relieved when one of his butterflies survives being accidentally stepped on ("Butterflies - Reprise"). However, Rapskullio can't paint Delilah back into the real world - they must wait for someone to open the book. Delilah and Prince Oliver share a dance ("Something To Hold On To").

Suddenly, Grace opens the book, and the Fairy-Tale Characters scramble to their storytelling positions. Orderlies place Delilah on a hospital gurney. She wakes up in the hospital, and the Doctor lets her know that she has a mild concussion after falling off the roof. When Delilah opens the book, Prince Oliver wants to be alone ("Something To Hold On To - Reprise").

The next day, Allie and her minions fake a "promposal" to Delilah from Prince Oliver. Delilah confesses to Jules that her "boyfriend" is a character in a book, and they bond over being outcasts ("Allie McAndrews"). They decide to track down the author of Between the Lines, Jessamyn Jacobs.

At Jessamyn's house, Delilah learns that the author published a single copy of Between the Lines to help her son get through a tough time. Delilah tries to explain to Jessamyn how the book speaks to her ("Can't Get 'Em Out"). Delilah tells Oliver that Jessamyn won't rewrite the ending of the book, and they say goodbye ("Between The Lines - Reprise"). Delilah closes the book as Jessamyn's son, Edgar, brings Delilah a glass of water. Delilah is surprised to see that Edgar looks exactly like Prince Oliver.

Delilah decides to change her story ("Finale - Part 1") and gets to work writing her next chapter.

Five years later: Delilah writes an article to be published by Teen Vogue, which she reads aloud, surrounded by her friends and family ("Finale - Part 2") at the New York Public Library.