Act One
The play opens in the early 1980s, at the ending of the story. Mrs. Johnstone, surrounded by others, including Mr. and Mrs. Lyons, and the Narrator, is standing over the bodies of Mickey and Eddie and sings “Tell Me It’s Not True” (“Overture”). The Narrator introduces the “story of the Johnstone twins” to the audience and the play then flashes back to the late 1950s.
30-year old Mrs. Johnstone lives in the Victorian inner-city slums of Liverpool. She describes her whirlwind romance with her husband, who, once attracted to her because of how she looked "like Marilyn Monroe," lost interest in her after multiple pregnancies and weight gain, and eventually left her for a younger, more attractive woman. Now a single mother, she discovers she's pregnant yet again ("Marilyn Monroe").
Heavily in debt and unable to support her seven children alone, Mrs. Johnstone takes a job as a cleaner for a local upper-middle-class couple, Richard and Jennifer Lyons. While talking with Mrs. Lyons, she mentions she's found out she's carrying twins, but can only afford to raise one more child. Mrs. Lyons, desperate for a baby but unable to conceive, suggests she give one of the babies to her ("My Child"). Mrs. Johnstone reluctantly agrees and is made to swear on the Bible to keep to the deal.
Mrs. Johnstone has the twins, and names the two children Michael (known as Mickey throughout the play) and Edward, but then regrets having agreed to give one away ("Easy Terms"). After keeping her deal with Mrs. Lyons, she returns home with baby Michael and lies to her older children, saying that the other baby died.
Mrs. Johnstone continues to work for the Lyons family, but Mrs. Lyons begins to feels she's too attached to Edward. She fires her, causing Mrs. Johnstone to demand her son back. Mrs. Lyons manipulates her into backing down by playing on her superstitious nature, telling her that "if twins separated at birth learn that they were once one of a pair, they will both immediately die" ("Shoes Upon the Table").
Years later, a seven-year-old Mickey meets Edward by chance. After learning that they share the same birthday, the two boys make a pact to become blood brothers, with Mickey nicknaming Edward "Eddie." Mrs. Johnstone finds them and sends Eddie away, fearing they'll find out they're twins. Later in the day, Mickey goes to Eddie's house, but Mrs. Lyons throws him out when she realizes that he's Edward's twin.
Mickey plays with some neighbourhood children, including his friend Linda ("Kids' Game"). Afterwards, Mickey takes her to see Eddie, and the three of them sneak off to play. Mrs. Lyons worries about Eddie's whereabouts ("Gypsies in the Wood"). The three are caught attempting to throw stones through a window by a police officer, and escorted home.
Mrs. Lyons, worried about Eddie's friendship with Mickey, persuades her husband they should move. Eddie goes to Mrs. Johnstone's house to say goodbye to Mickey and she gives him a locket, which she claims contains a picture of herself and Mickey. Edward asks Mrs. Johnstone why she doesn't simply move away, causing her to dream about the seemingly impossible possibility of her moving away and beginning a new life ("Bright New Day (Preview)"). Mickey goes to visit Eddie but finds him gone ("Long Sunday Afternoon / My Friend").
During the early 1970s, the Johnstone family are moved from the condemned inner-city slums of Liverpool to a new council house in the nearby overspill town of Skelmersdale ("Bright New Day").
Act Two
Act Two rejoins the twins when they are 14 years old, some time in the early-to-mid 1970s. The Johnstone family are enjoying a better life now they have moved to a new home and a new area, and they have not seen Eddie in all this time ("Marilyn Monroe 2"). Mickey has now developed a crush on Linda, who is obviously interested in him too, but Mickey does not know how to approach her and is embarrassed by her honesty to being attracted to him. During their journey to school Sammy, Mickey's older brother, pretends to be 14 to get a cheaper bus ticket. When he is confronted his violent nature becomes obvious; he swears violently at the driver, threatens him with a knife, steals some money and escapes.
Eddie is suspended from his boarding school for refusing to give up his locket to a teacher. Meanwhile, Mickey refuses to pay attention or co-operate during a class in his school, insulting the teacher, and is suspended. Linda is also suspended for defending him. When he returns home, Eddie refuses to tell Mrs. Lyons about the locket's contents, and when she takes it and sees the picture inside she panics, and immediately assumes it is a picture of Eddie. She grows paranoid, having once thought she had buried the past by moving away, and questions Mrs. Johnstone's presence in their lives ("The Devil's Got Your Number"). Eddie and Mickey, now teenage and insecure, both reminisce over their blood brother status, and after seeing each other but not realising they are seeing their blood brother, think about how they wish they had the qualities the other guy has ("That Guy"). After Mickey and Linda walk through a field in the countryside surrounding Skelmersdale, where Linda expresses her frustration at how Mickey has not yet asked her out, Mickey and Eddie meet by chance once again, revealing that the Lyons family moved close to Skelmersdale (where the Johnstone family now live) and they discover that they live near each other. Eddie gives Mickey humorously inexperienced advice on how to talk to Linda, and invites him to watch a pornographic film with him to "see how it's done".
An increasingly mentally deranged and paranoid Mrs. Lyons further questions whether she is truly free from Mrs. Johnstone ("Shoes Upon The Table (Reprise)") as Mickey asks his mother for money to see a film while reintroducing Eddie. After she realises it is a pornographic film, the three have a humorous moment, before Mrs. Johnstone gives them the money and they leave. Mrs Lyons, by this point clearly mentally ill, discovers Mrs. Johnstone's house and confronts her, believing that she followed her after they moved. After she admits that she “never made him [Eddie] mine”, she offers to pay off Mrs. Johnstone again. After Mrs. Johnstone stands her ground and declares she will not be paid off again, stating that she has made a good life for herself, an enraged Mrs. Lyons attempts to attack Mrs. Johnstone with a knife, but a now strong-willed Mrs. Johnstone fights back and kicks her out, with Mrs. Lyons fleeing in terror. Mrs. Lyons continues to deteriorate into insanity and it is implied that she has developed a reputation for madness. (“Mad Woman On A Hill”).
Mickey, Eddie, and Linda spend each summer as teens together, taking the play to the end of the 1970s, when an 18-year-old Eddie reveals to Linda that he is leaving for university in Liverpool the following day, but has not told her or Mickey. Linda reveals that Mickey still hasn't asked her out, prompting Eddie to tell her what he would say to her if he were Mickey. Secretly, he is revealing his true feelings but has not acted on them out of respect for Mickey ("I'm Not Saying A Word"). Eddie leaves for university in Liverpool, but not before encouraging Mickey to ask Linda out.
During Eddie's absence, Linda gets pregnant, and she and Mickey quickly marry and move in with Mrs Johnstone. Mickey is then made redundant from his factory job due to the recession of the early 1980s, which hits Merseyside particularly hard, and Mickey joins thousands of other Merseysiders on the dole shortly before Christmas (“Take A Letter, Miss Jones"). Eddie returns at Christmas ready to party and have fun, but Mickey realises that they are now very different; after a small argument, they part. Mickey is persuaded to assist his brother Sammy, who now engages in criminal acts, in a robbery, to earn money to support Linda and their baby daughter Sarah. The robbery goes bad, and Mickey becomes an accessory to a murder committed by Sammy. He is sentenced to seven years in prison, and the incident destroys Mickey mentally.
In prison, Mickey is diagnosed as chronically depressed. When released early for good behaviour, he is still dependent on anti-depressants. He becomes withdrawn and turns away from Linda ("Marilyn Monroe 3"). Linda, unable to get Mickey off the anti-depressants, contacts Eddie, who is now a local councillor, who gets them their own house in Liverpool and Mickey a job ("Light Romance"), taking the focus of the play back to Liverpool. Linda worries about Mickey and continues to meet up with Eddie. A mentally ill Mrs. Lyons, now seemingly wanting to get back at Mrs. Johnstone in any way possible, even if it involves possibly being harmful to Eddie, sees Eddie and Linda together and tells Mickey about it, suggesting that the two are having an affair. Distraught over Eddie and Linda's 'affair,' Mickey grabs the gun that Sammy hid before he got arrested and storms down to the council offices to confront Eddie ("Madman"), who is giving a speech as Mickey storms in with the gun. Mickey asks why Eddie would take away the one good thing that Mickey had – Linda. Eddie denies this intention, and the police enter, demanding that Mickey put the gun down. After being informed by Linda of the incident, Mrs. Johnstone runs in and, in an attempt to stop Mickey from shooting Eddie, tells the two brothers the truth. Mickey furiously despairs that he was not the one given away, because then he could have had the life given to Eddie. Enraged, Mickey gestures with the gun toward Eddie and accidentally pulls the trigger. The gun fires, killing Eddie, with the police then shooting and killing Mickey.
As Mrs. Lyons had suggested all those years earlier, the superstition that the two brothers would die if they discovered the truth has finally materialised, and the narrator questions whether the differing backgrounds of the two boys was more to blame than superstition. ("Tell Me It's Not True").
