Act I takes place during Chuck Krantz’s childhood. When he is seven, Chuck anticipates a baby sister named Alyssa, but his parents die in a car crash on an I-95 overpass. He is with his paternal grandparents, Albie and Sarah Krantz (whom he calls “Zaydee” and “Bubbie”), at the time. The accident also claims Chuck’s unborn sister, and the Krantz house becomes a place of grief for the next year and a half. Chuck recalls his mother laughing and crying at the same time when he said the name Alyssa sounded like rain.

Chuck’s grief lifts first, helping pull his grandparents from their sorrow. When Chuck is 10, the family takes a trip to Disney World, marking a turning point in their collective mood. Afterward, Sarah begins singing and cooking again. She often asks Chuck to dance with her in the kitchen—calling him “Henry” for reasons unknown to him—teaches him jitterbug steps, and tells him he is a natural dancer.

The Krantz Victorian house has a locked cupola at the top. Chuck asks about it repeatedly; his grandparents claim the floor is rotted and the view is uninteresting. Just before Chuck’s eleventh birthday, Albie hints at a darker reason for keeping it locked.

One night just before Chuck’s eleventh birthday, Albie gets drunk watching a baseball game. Chuck raises the subject of the cupola again, mostly to make conversation. Albie mutes the television and tells Chuck that if he went up there, he might see more than he wanted.

Albie explains that the house is a genuine Victorian built in 1885 and that he has rarely visited the cupola himself. He reveals the real reason it is locked: The cupola is full of ghosts. He cryptically mentions seeing something related to the Jefferies boy shortly before the boy died, and something involving Henry Peterson before Peterson’s death. He also refers to a vision of Sarah and bread, saying the waiting is the hardest part.

Sarah returns home from visiting a neighbor. Chuck asks who Henry Peterson was, but Albie, hearing his wife come in, feigns sobriety and redirects attention to the game.

Sarah sends Albie out to sober up. After he leaves, she asks Chuck if Albie was talking about ghosts in the cupola, dismisses the stories as drunken rambling, and tells Chuck not to pay too much attention.

Chuck asks about the Jefferies boy. Sarah explains that he was a neighborhood child killed by a drunk driver years earlier when he chased a ball into the street. She denies that Albie saw it beforehand, claiming he was either mistaken or joking. Chuck notices she avoids his eyes, and he realizes she is lying.

After this conversation, Chuck becomes both frightened of and fascinated by the cupola. When his grandparents are out, he sometimes dares himself to climb the short stairs and touch the padlock, certain that hearing it open would kill him with fright.

The cellar of the Krantz house is well-lit and smells of sawdust from Albie’s woodworking hobby. Chuck finds a box of his grandfather’s old Hardy Boys books and starts reading them, until Sarah gives him Agatha Christie’s The Murder of Roger Ackroyd instead. Chuck falls in love with Hercule Poirot and reads nearly two dozen Christie novels.

While reading Murder on the Orient Express in the backyard hammock, Chuck looks up at the cupola window and decides to investigate it like Poirot would. He brings freshly baked muffins to Mrs. Stanley, the neighborhood gossip, as a pretext, and over tea employs a Poirot tactic: sharing a small piece of information to encourage her to share in return.

Chuck asks about Henry Peterson. Mrs. Stanley reveals that Peterson was Chuck’s father’s bookkeeper who died by suicide after his wife left him. Back home, Chuck connects his grandfather’s visions to the deaths of the Jefferies boy and Peterson. He deduces that Albie must have seen a vision of Sarah’s death involving bread, which explains why Albie said the waiting was hard. Chuck realizes he, too, is now waiting for this premonition to come true.

On the last day of sixth grade, Chuck’s teacher, Miss Richards, tries to read Walt Whitman’s “Song of Myself” to the rowdy class. One line strikes Chuck: “I am large, I contain multitudes” (90).

After class, Chuck stays behind and asks Miss Richards what the line means. She explains that his head contains an entire world and that this inner world will grow bigger and more complex with each year that he lives.

Chuck is overwhelmed by the thought of a whole world inside his skull. He thinks of the Jefferies boy and Henry Peterson, imagining their inner worlds going dark like a room when the light is switched off. As he leaves, he asks Miss Richards if she believes in ghosts. She says she believes memories are ghosts, but not literal apparitions.

In August, after sixth grade, Sarah dies of a stroke at Zoney’s Go-Mart. She is nearly 65. The Krantz house becomes a place of sadness again, but Chuck senses that along with grief, his grandfather feels some relief that the dreaded wait is over.

Before starting seventh grade, Chuck goes to Zoney’s and asks a clerk where his grandmother died. The clerk directs him to the third aisle and tells him that Sarah collapsed while reaching for bread, pulling down nearly everything on the shelf. Chuck realizes his grandfather’s vision was accurate, as he had already suspected.

At the beginning of seventh grade, Chuck sees a flyer for Twirlers and Spinners, the school dance club. Remembering his grandmother asking him to dance, he decides to join. Chuck proves to be the best dancer by far. The instructor, Miss Rohrbacher, usually pairs him with clumsier dancers to help them improve, but near the end of each session she pairs him with Cat McCoy, an eighth-grader and the best female dancer. Dancing with Cat is joyful; they look into each other’s eyes and laugh.

One day in October, Chuck performs a moonwalk to “Billie Jean,” amazing the group. Cat asks him to teach her, and soon everyone is moonwalking. Cat suggests they perform together at the upcoming Fall Fling. Chuck worries he is too short, but Cat offers him her brother’s Cuban heel shoes. Chuck tries them on and loves them. They are slick and perfect for dancing.

Chuck attends the Fall Fling alone. Cat’s boyfriend, Dougie Wentworth, does not dance, so Cat dances with Chuck frequently. Chuck waits for the right song, thinking of his grandmother.

When the DJ plays the song Chuck used to dance to with Sarah, Jackie Wilson’s “Higher and Higher,” Chuck knows it is time. He and Cat perform a spectacular routine. When they execute a double moonwalk, the dance floor clears and the students form a circle around them, clapping. They finish with Cat spinning and collapsing backward into Chuck’s arms while he drops into a split. Cat kisses the corner of his mouth, and 200 kids cheer. Someone shouts for an encore, but Chuck and Cat shake their heads, knowing they cannot top it.

Six months before dying of a brain tumor at age 39, Chuck tells his wife, Ginny, the truth about the crescent-shaped scar on his hand. He has previously claimed Dougie Wentworth pushed him into a fence after the Fall Fling dance, but that was a lie.

The narrative returns to the night of the dance. After the performance, euphoric and overheated, Chuck walks outside alone into the cool night air. He reflects on the vastness of the universe and the idea of containing multitudes, feeling wonderful. While moonwalking and twirling under the basketball hoop, his outstretched hand strikes a protruding jut of wire on the chain-link fence, leaving a permanent crescent-shaped scar.

Ginny asks why he lied about something so insignificant. Chuck’s failing mind cannot articulate the real reason: the scar is part of the larger, unbelievable story of the haunted Victorian house, and the lie made it feel more meaningful.

Four years after the Fall Fling, Albie dies of a heart attack on the steps of the public library, returning a copy of The Grapes of Wrath. He leaves Chuck his entire estate, which is enough to pay for college and later help buy a house with Ginny.

A day before his maternal grandparents arrive to look after him until college, Chuck opens a manila envelope from the funeral parlor containing Albie’s personal effects. Among the items is his grandfather’s keyring. Holding the keys, Chuck climbs the short flight of stairs to the locked cupola door, finds the right key, unlocks the padlock, and pushes the door open.

Chuck enters the cupola and finds it empty. The floor is solid, disproving his grandparents’ old lie about rot. The view is unremarkable, exactly as his grandfather had said.

As Chuck turns to leave, he sees a hospital bed in the center of the room with an unconscious man in it and hears the beeping of a heart monitor. The man’s hand lies outside the coverlet, and Chuck observes the crescent-shaped scar on the back of it with no surprise. He understands this is how his grandfather saw Sarah lying dead among scattered loaves of bread.

Chuck steps closer, wondering how old the man is and how long his own wait will be. The vision vanishes with one final beep. He insists to himself that it was not real and that he will live his life fully. He affirms that he is wonderful, deserves to be wonderful, and contains multitudes. He closes the door and snaps the padlock shut.