Papa gathers the Vanderbeeker family to announce their landlord Mr. Beiderman will not renew their lease.

The five Vanderbeeker children form Operation Beiderman, a plan to win over their cranky landlord with kindness.

Jessie drops the carefully prepared breakfast tray and shatters Hyacinth's beloved teapot outside Mr. Beiderman's door.

Mr. Beiderman frightens Hyacinth at his apartment door when she tries to deliver her handmade placemat.

Laney visits neighbors Miss Josie and Mr. Jeet, who reveal that Mr. Beiderman once loved jazz music.

Mr. Beiderman phones Mama to announce he is showing the apartment to prospective renters almost immediately.

Papa takes the children to buy a Christmas tree and the whole family decorates it together at home.

The Vanderbeeker children canvas their entire neighborhood collecting neighbors' signatures on a petition to let them stay.

Oliver discovers the Duke Ellington record the children left for Mr. Beiderman smashed inside the trash bag.

The children travel to City College to learn about Mr. Beiderman but a rude receptionist turns them away.

Mr. Beiderman calls Papa to complain angrily about the petition and the flood of phone calls from neighbors.

Papa expresses disappointment and requires each of the children to write a formal apology letter to Mr. Beiderman.

Isa grabs her violin and plays passionately outside Mr. Beiderman's door; he opens it and breaks down in tears.

Mr. Beiderman opens his apartment door on Christmas morning and invites all five Vanderbeeker children inside.

Mr. Beiderman tells the Vanderbeeker family they are welcome to remain in the brownstone.

The Vanderbeeker children learn their landlord Mr. Beiderman is not renewing the family lease and launch Operation Beiderman to win his heart. Their early attempts at kindness are disastrous, and Mr. Beiderman only grows more hostile, even showing the apartment to new renters. The children escalate their efforts with a neighborhood-wide petition, but the plan backfires when Mr. Beiderman angrily calls their father and Papa orders them to stop. On Christmas Eve, Isa makes a desperate, bold move and plays her violin at Mr. Beiderman's door, cracking through his cold exterior and moving him to tears. The breakthrough leads to a remarkable Christmas morning reunion in which Mr. Beiderman invites the children inside, reveals the painful truth behind his grief, and tells the family they can stay.

The headline events of the Vanderbeekers' fight to save their home.

Oliver climbs to his treehouse and radios best friend Jimmy L by walkie-talkie to share the devastating news of the move.

Mailman Mr. Jones tells Hyacinth that before becoming a landlord, Mr. Beiderman was a college art history professor.

At Castleman's Bakery, Benny Castleman asks Jessie whether twin sister Isa would agree to go to the eighth-grade dance with him.

Jessie panics and tells Benny that Isa would say no to the dance, then immediately regrets speaking for her sister.

Isa visits Castleman's Bakery with friend Allegra and Benny is uncharacteristically cold and distant toward her.

Oliver rescues a box of old jazz records from the donation pile while helping Mama pack moving boxes.

The children leave a Duke Ellington jazz album outside Mr. Beiderman's apartment door as a thoughtful gift.

Mama and Papa stay up late discussing their slim housing options and the frightening possibility of relocating to Ottenville.

Laney secretly delivers a small Christmas tree outside Mr. Beiderman's door, deciding he needs one more than anyone.

Oliver delivers Mama's Christmas cookies to neighbors and enlists his friend Angie to research Mr. Beiderman online.

On the walk home from City College, Oliver deliberately gives wrong directions to the kind prospective tenant Mr. Rochester.

Hyacinth discovers a stray mother cat with kittens and quietly fashions them a warm makeshift outdoor shelter.

Laney and Mr. Jeet delight the Christmas dinner guests with a performance showcasing tricks they taught Paganini the rabbit.

Papa delivers an emotional Christmas dinner toast thanking his neighbors for enriching his children's lives.

Neighbors and Mr. Beiderman lean out the brownstone windows to cheer Isa and Benny as they leave for the school dance.

While the Vanderbeeker children execute Operation Beiderman, the story is enriched by warm community relationships and small personal dramas that deepen the stakes. Oliver shares the crisis with his best friend Jimmy L, mailman Mr. Jones drops a clue about Beiderman's past, and Jessie makes a fateful decision at the bakery that quietly starts a rift between the twins. The children gather intelligence about their reclusive neighbor, leave him a jazz record, and even misdirect a kind prospective tenant on their way home from City College. A tender Christmas dinner performance at Miss Josie and Mr. Jeet's fills the story with warmth even as hope seems lost. The novel closes with a triumphant epilogue as the entire brownstone community leans out their windows to celebrate Isa and Benny heading off to the school dance.

The community bonds and personal dramas running alongside the main story.

The Vanderbeeker children resolve to win over Mr. Beiderman with kindness and gifts rather than retaliate against him.

Hyacinth asks Papa why Mr. Beiderman hates them, and Papa explains he is not hateful but simply deeply unhappy.

After Hyacinth's frightening encounter, Oliver secretly writes Mr. Beiderman an anonymous threatening letter to defend his family.

Hyacinth and Laney eavesdrop from the stairs as Mama and Papa discuss the possibility of moving far away to Ottenville.

After learning of the Ottenville possibility, the Vanderbeeker children hold an emergency midnight meeting to intensify their plan.

Jessie visits Isa's beautifully decorated basement violin studio for the first time and the sisters share a tender moment.

Angie arrives with research revealing that Mr. Beiderman's wife and teenage daughter Luciana were killed in a tragic accident.

Mrs. Castleman slips Isa a mysterious envelope containing a newspaper article about the deaths of Mr. Beiderman's family.

At Castleman's Bakery, Isa confronts Benny and discovers that Jessie told him Isa would refuse to go to the dance.

Isa storms home and confronts Jessie, demanding she never make decisions for her; the sisters stop speaking entirely.

Hyacinth wraps one of the stray kittens in her scarf and secretly delivers it to Mr. Beiderman's door.

Mr. Van Hooten pulls Isa aside to reveal that Mr. Beiderman's daughter Luciana was his student and Isa's violin was hers.

Isa finds Jessie hiding on the fire escape and the twins reconcile as Jessie confesses she feared losing her sister.

Franz drags Hyacinth to the front door, where she finds the kitten returned with a note from Mr. Beiderman asking her to visit.

Inside his apartment, Mr. Beiderman explains that hearing Isa play Luciana's favorite song on her violin was why he refused to renew the lease.

The most important turning points in the story are the small decisions and shocking discoveries that reshape how the Vanderbeekers understand Mr. Beiderman and each other. The children begin by choosing kindness over revenge and soon piece together clues about their reclusive landlord, learning he is less a monster than a deeply broken man. Angie's research and a mysterious envelope from Mrs. Castleman reveal the full tragedy of Beiderman's past, while Jessie's interference with Benny ignites a painful rift between the twins that threatens their unbreakable bond. Isa's confrontation at Mr. Beiderman's door and Mr. Van Hooten's revelation about Luciana's violin finally unlock the true reason the family was asked to leave. When Beiderman himself reaches out first by returning the kitten with a note, the story turns decisively toward forgiveness and belonging.