Cora celebrates her 12th birthday at Pete's pizza with Dad and Grams, keenly feeling Mabel's absence.

Quinn leaves a box filled with time travel articles on Cora's doorstep as a birthday gift.

Cora finally opens Quinn's box and discovers a collection of articles about time travel and wormholes.

Quinn leads Cora through the woods to a large oak tree she believes could contain a wormhole.

Cora messages Quinn and they agree to structure their time travel attempt as a scientific experiment.

Cora expands her research question to include saving Parker as well as Mabel, and Quinn is deeply moved.

Quinn and Cora sit back-to-back in the oak tree and visualize the shooting morning, but no wormhole appears.

Quinn confesses to Cora that she saw Parker opening their father's gun safe weeks before the shooting.

Cora furiously ends her renewed friendship with Quinn and resolves to continue searching for the wormhole alone.

Cora's father shares her late mother's belief that time has a shape, much like the shape of thunder.

Cora hears thunder at the Fall Fair and runs out of the gym into the stormy woods.

Quinn pulls an unconscious Cora out of a flooded creek and calls for emergency help.

Cora wakes in the hospital and fully accepts for the first time that Mabel is permanently gone.

Cora begins packing Mabel's belongings from their shared bedroom and calls Quinn to come help.

Quinn and Cora visit the oak tree on the anniversary of the shooting, burying a letter and planting violet seeds.

After her sister Mabel is killed in a school shooting carried out by her neighbor Quinn's brother Parker, Cora spends her twelfth birthday grieving. When Quinn leaves a box of time travel articles on her doorstep, the two former best friends reunite around a desperate plan to find a wormhole and undo the shooting. They conduct research, visit a meaningful oak tree in the woods, and attempt to visualize the past, but their plan collapses when Quinn admits she saw Parker take their father's gun and said nothing. Cora breaks off the friendship again and tries to reach the wormhole alone during a thunderstorm, slipping into a flooded creek and being rescued by Quinn. Waking in the hospital, Cora finally accepts the reality of Mabel's death and begins to move forward. The girls find closure together, planting seeds and burying a letter at the oak tree on the anniversary of the shooting.

The core journey from birthday grief to healing through failed time travel.

Quinn spends time alone in the school library researching time travel after becoming a social pariah.

Quinn approaches Cora at school to share her time travel theory, but Cora dismisses her and walks away.

Grams argues with Cora until she relents and goes upstairs to open Quinn's birthday box.

Cora is overcome with grief at the oak tree and runs away, declaring the time travel plan is insane.

Quinn's parents argue loudly at dinner about whose fault Parker's actions were, while Quinn watches silently.

During a lockdown drill, Cora freezes in her seat and her teacher must coax her into the supply closet.

Unable to sleep, Cora writes a formal scientific observation, question, and hypothesis about traveling back to save Mabel.

Cora is substituted out of a Quiz Bowl away match because anxiety about the emergency exits makes her unable to focus.

Mia confronts Cora after the Quiz Bowl match, accusing her of abandoning their friendship to spend time with Quinn.

Cora tearfully admits to Grams that spending time with Quinn makes her feel like a bad sister to Mabel.

Cora's father takes her to a Middle Eastern restaurant and they talk about exploring their shared Arab heritage.

Quinn confesses to Mrs. Euclid that she saw Parker at the gun safe, and Mrs. Euclid urges her to tell someone.

Cora and Quinn lay out their siblings' possessions at the tree and share a hug using their childhood heart signal.

Quinn finds Mia and Owen at the Fall Fair, learns Cora headed into the woods, and races after her.

Mia visits Cora at home after the accident, admits her jealousy over Quinn, and they reconcile their friendship.

While Cora and Quinn's time travel mission drives the story, these events trace the smaller but equally important moments that shape their healing. Quinn's lonely library research and Cora's reluctant opening of the birthday box set the friendship's slow restart in motion. School life intrudes through a traumatic lockdown drill and Cora's distracted Quiz Bowl performance, revealing how deeply the shooting has marked both girls. Arguments with Mia, tearful confessions to Grams, and Quinn's brave disclosure to Mrs. Euclid all add texture to the girls' emotional journeys. A quiet dinner at a Middle Eastern restaurant and a reconciling visit from Mia show that healing also comes through ordinary moments of connection. Together, these events reveal the full scope of what Cora and Quinn are carrying as they try to move through grief.

The quieter milestones of grief, friendship, and everyday courage.

Quinn reads an article calling time travel 'possible' and feels a real spark of hope for the first time.

In a letter, Quinn admits to Parker that she was the only one who truly saw him but said nothing.

Cora finds Quinn near the athletic fields after school and agrees to investigate the time travel articles further.

During a lockdown drill in art class, Quinn panics and pictures the oak tree wormhole to calm herself.

Quinn lies on Parker's bed and tries to ask her father deeper questions, but he only asks if she is okay.

Cora confronts Quinn at the oak tree, asking directly whether Parker targeted Mabel because she was Muslim.

Quinn visits the oak tree alone and wonders if her memory of seeing Parker at the gun safe is the missing key.

Dr. Randall asks Cora about her final morning with Mabel, and Cora admits they argued and she mocked Mabel's lip gloss.

Quinn's mother shuts herself in her bedroom when Quinn tries to force a conversation about Parker's crimes and the guns.

Cora asks her father how to say the word 'complicated' in Arabic while discussing her relationship with Quinn.

Quinn's father turns back to the television when Quinn tries to have a meaningful conversation about Parker.

Quinn resolves at the Fall Fair to find Cora and make amends, convinced their friendship still matters.

Quinn tells her parents she saw Parker with the gun, admits she feels responsible, and asks for professional help.

Grams brings empty boxes into Cora's bedroom and tells her it is time to pack up Mabel's things.

Quinn writes her final letter to Parker, declaring she can both love him and never forgive what he did.

Beneath the surface of the main plot, a series of key revelations and turning points quietly determine how Cora and Quinn will heal. Quinn's early discovery of the word 'possible' in a time travel article sparks the entire mission, while her private letter admitting she saw Parker at the gun safe reveals the guilt she has been carrying from the start. Moments like Cora's confrontation about Parker's racism, Quinn's failed attempts to speak honestly with each of her parents, and Dr. Randall's question about Cora's last morning with Mabel force both girls to face truths they have been avoiding. As the story reaches its climax, Quinn's act of telling her parents what she saw and demanding professional help marks her most important step toward healing. Grams's gentle push for Cora to pack away Mabel's belongings, and Quinn's final letter accepting the contradiction of loving and hating her brother, complete both girls' emotional arcs. These are the quiet, decisive moments that make the story's hopeful ending possible.