The following synopsis is based on the Broadway version of the show.
Act 1
The show opens with J.M. Barrie dressed in black with Peter Pan and Tinker Bell (represented by a light) on stage. Barrie is thinking out loud about his life. He also is finding clarity and accepting himself ("If the World Turned Upside Down").
Time winds back and James M. Barrie states that the story happens in London, 1903. We see a party hosted at Barrie’s house by his wife Mary and himself, after the opening night of his latest play The Wedding Guest. Charles Frohman, the show's producer, is attending the party. The party-goers say that it's the "best party of the year", however the play failed to please the audience. Lord Canaan, a wealthy and pompous man, is also attending the party and flirts with Mary ("All of London is Here Tonight").
A month later, Barrie meets Frohman at Kensington Garden and tells him that he is almost finished with his next play to substitute the failure that The Wedding Guest was. The Llewelyn Davies boys, Peter, Michael, Jack and George, play as pirates around the park and interact with Barrie, except Peter who sits and reads. Sylvia, their mother, tries to get them to behave, but fails, ultimately joining the play ("The Pirates of Kensington"). She meets Barrie and confesses that she did not enjoy his latest play as it felt that he recycled lots of elements from the previous ones. Barrie asks Peter why did he not play with his brothers, to which he responds that he finds it all silly.
Back at their home, Mary is waiting for Barrie to go to a formal dinner, complaining that he is late. Barrie arrives and tells her that he met Sylvia Llewelyn Davies and her children. Mary says that Sylvia’s husband died of cancer of the jaw and that her mother, Mrs. du Maurier, is very influential and thus they should invite them for dinner. Mary leaves alone for the dinner and Barrie tears his newest play up, believing it to be rubbish.
The next day, Barrie meets Frohman and the acting troupe, who are expecting to read the new play but are frustrated to discover Barrie threw it away. Frohman says that if Barrie cannot write another play fast he will find another writer. Later, Barrie meets with the Llewelyn Davies at the park. Barrie says to Peter that he started writing when he was his age to escape reality. He stimulates him and the rest of the family to use their imagination ("Believe"). Barrie invites Sylvia, her mother and the boys to the dinner his wife is planning.
The following month, the dinner occurs. Mrs. du Maurier tells Mary she is intrigued by Barrie’s relationship with her daughter and grandsons. Frohman arrives with Lord Canaan in an attempt to persuade him to invest in their next play. Barrie gives Peter a notebook as a present, incentivizing him to write a play. During dinner, inspired by a spoon reflecting the light, Barrie claims that the light is a fairy. Bored by the grown-ups' talk, Barrie stops time with his imagination and is joined by the boys, Sylvia and the servants to have their own party ("We Own the Night (The Dinner Party)"). The time unfreezes and Lord Cannan leaves the party offended by Barrie's behavior. Mary scolds him telling that he is behaving like a child.
Mrs. du Maurier gives Sylvia and the children a carriage ride home. Sylvia talks with her mother outside, who is worried that her relationship with Barrie is hurting her prospects. Sylvia is sick and avoiding telling her boys, since her husband recently died. Sylvia wishes to spend the rest of her life living it to the fullest with her boys and contemplates the happiness Barrie has brought to her ("All That Matters").
On another night inside the house, the boys play in their pajamas and refuse to go to sleep ("The Pirates of Kensington (Reprise)"). Barrie is there and watches the boys jumping on their beds, and is inspired as they look like they are flying. They discuss what they should play and Peter suggests they pretend to be castaways and Barrie should be an Indian chief. Peter is offended as Barrie says that as the chief he would raise the castaways as his sons, claiming he is not their father. The boys fight and Sylvia sings them to sleep ("Sylvia's Lullaby"). Barrie confides in Sylvia that when he was Peter's age his brother died, so he knows the pain of loss. Sylvia gives Barrie a thimble, claiming it protects from pain while sewing. Barrie claims his brother went to Neverland, a place he invented where no one ever grows older ("Neverland").
In the theater, Barrie presents his idea based on Neverland for his play to Frohman. Frohman is outraged as he believes the concept will not attract an audience. He also alerts Barrie to comments people have been making about his relationship with Sylvia and the boys. Barrie goes home and finds Mary alone with Lord Canaan. She confronts him with his diary, where he writes a lot about Sylvia, but not about her. She leaves him. Barrie goes to the Llewelyn Davies residence to see Sylvia and the boys, but Mrs. du Maurier stops him at the door claiming Sylvia is in bed and that their relationship is hurting her. Barrie is flustered by all the different pressures he is facing ("Circus of Your Mind").
Seemly defeated, Barrie is visited in his imagination by Captain Hook. A figment of Barrie’s frustrations and strife, Hook convinces Barrie to continue with the play and write him in as the new villain. It is communicated that Hook is a villainous side to Barrie’s personality, but one that he needs nonetheless ("Live by the Hook"). Barrie strides, in his imagination, on a pirate ship with the support of Hook and the pirates. He realizes that he doesn’t need to allow anyone else’s opinion to change his. If he believes in his own work, that's all that truly matters ("Stronger").
Act 2
At the beginning of act II, the Llewelyn Davies boys visit Barrie at the theater as the company is reluctant and confused, testing some elements of the new play ("The World is Upside Down"). Chales invites the actors to drink at The Swan, a tavern. Sylvia arrives to take the children home. She has heard that Mary left him. The children convince her to go with Barrie to the tavern as Elliott, Frohman’s assistant, takes them home. Sylvia is afraid that she was part of the reason Mary left Barrie, but he assures her that the separation was long in the making. The two play in the empty theater stage with the shadows cast by the ghost light and try to put to words what their relationship means to each other ("What You Mean to Me").
At the tavern, the company is afraid the play will be a failure. Barrie arrives with Sylvia and tells Frohman that they need children in the audience, asking him to keep 25 seats to orphans. Sylvia remarks that Frohman and the actors have forgotten how to play. They reminisce about old times when they used to live more whimsical and free in their youth ("Play").
In the Llewelyn Davies backyard the boys prepare a play of their own, written by Peter, who is afraid he is not a real writer. His brothers tell him to be proud of what he did and encourage him based on what Barrie has been teaching them ("We're All Made of Stars"). Barrie and Sylvia arrive to watch the play. Barrie asks Peter permission to use his name as the protagonist. They start Peter's play, but during the presentation, Sylvia starts to cough very badly, to which she claims it is only a silly chest cold. Barrie sees blood on the handkerchief, but Sylvia refuses to pursue treatment as she does not want the boys to relieve the experience they had with their father and asks Barrie to take care of her children. Barrie takes Sylvia inside and Peter starts destroying the set of the play. Barrie comes back to check on Peter, who lashes out at him, saying that grown ups are always lying and he does not believe that his mother has just a chest cold, for something similar happened to his father. In rage, he tears his play apart from the notebook Barrie gave him. Barrie comforts him, letting him know that life can be difficult but imagination can help him escape for a bit when needed ("When Your Feet Don't Touch the Ground").
On opening night the company is very nervous, but Frohman encourages them as they prepare to present Peter Pan ("Something About This Night"). Barrie arrives at the Llewelyn Davies residence to pick up the family to see the play. Mrs. du Maurier stops him at the door and forbids him to see her daughter. George intervenes and lets Barrie in, confronting his grandmother. Sylvia is not feeling well and cannot leave the bed, so the children have decided to stay with her. Barrie decides to stay with them as well and miss the opening night to his own play. Sylvia insists that he goes and takes one of the boys with him, as she wants a full report. Michael, Jack and George insist that Peter should be the one to accompany Barrie. Before he leaves, Sylvia gifts him with his notebook, to which she pasted his play back together.
At the theater, Frohman greets the audience, while at the Llewelyn Davies' residence, Charles, George and Michael prepare to go to sleep while Sylvia and Mrs. du Maurier put them to bed. Barrie and Peter arrive with the whole cast claiming that the theater was just a dress rehearsal, for the real opening night would take place at their residence. Peter says that the main character has his name, but the real Peter Pan is Barrie himself. The company presents the show while the family watches amused as they recognize elements of their times together that inspired the play. Sylvia is sprinkled with fairy dust and flies off with Peter to Neverland ("Neverland (Reprise)").
Barrie appears wearing the back clothes in which he started the first scene, showing that he has been mourning Sylvia. He meets Mrs. du Maurier at the park and she explains to him that Sylvia asked them to have joint guardianship of the boys in her will, which he accepts. Barrie then meets Mary accompanied by Lord Canaan. Mary praises Barrie’s play while Lord Cannan acts childishly. Frohman appears next, claiming they are going to make a lot of money with the success that Peter Pan is, to which Barrie responds that he will donate all the profit to a children's hospital. Peter appear next, holding a play which he is working on. He says he is missing his mother, to which Barrie responds that he can visit her anytime he likes in Neverland. The boys appear next and Jack calls Barrie "father" for the first time. Mrs. du Maurier, seeing with new eyes the positive impact Barrie had on the children, says that Sylvia will keep guiding them from Neverland and is joined by Barrie, the boys and the rest of cast in concluding that make believe can help you navigate the world ("Finale").
