Elizabeth Zott's life continues to change tremendously on Lessons In Chemistry Season 1 Episode 4, as the world shifts around her.

Brie Larson's Elizabeth is challenged with enduring unplanned, unwanted motherhood in a pivotal episode where multiple timelines come into play.

Elizabeth begins the episode in labor, her pain level high as she powers through difficult contractions in a delivery ward.

By the time she's ready to push, Elizabeth is in so much pain that a nurse gives her some pain medication, causing her to hallucinate Calvin.

The moment allows Elizabeth the clarity she needs to move into motherhood. Though the painkillers cause her to pass out, she wakes up with a newborn baby girl in her care.

Naming her daughter Mad after how she's feeling in the moment, it only takes a few moments for the viewers to watch Elizabeth's entire life change.

Elizabeth's first days with her daughter aren't easy, pushing her to the emotional brink as she can't get the baby to stop crying.

Brie Larson's frenzied, frazzled Elizabeth is a fascinating mixture of anger and agitation as she moves reluctantly into her new role, uncertain how to proceed.

Thankfully for Elizabeth, Harriet Sloane is across the street and happy to help. The friendship between Elizabeth and Harriet has been slow to build but rich as it's unfolded.

Harriet comes to Elizabeth's rescue several times throughout "Primitive Instinct," making it clear motherhood doesn't come easy.

The dynamic between Elizabeth and Harriet was initially challenging, especially when Elizabeth and Calvin first got together.

With Harriet understanding Calvin was putting his relationship over his obligations to her, she first retreated from her friendship with her neighbor in anger.

Calvin's unexpected death hit Harriet hard, pushing her into a tough place as she tried to explain what happened to her children.

Aja Naomi King's Harriet, dealing with a deployed husband, a household with her children, and a government looking to put a highway through her neighborhood, was filled with mixed emotions upon Calvin's death.

Her grief struck hard, but her bond with Elizabeth was tough to come by.

The pair strike up an unlikely friendship when Elizabeth finally turns to Harriet for help.

Struggling in her new era of motherhood, Elizabeth comes to Harriet in a moment of weakness, admitting how she's felt with a screaming newborn in her arms.

Harriet, whose friends are in the other room listening in, comforts Elizabeth, sharing that every new mother feels in over their head at the beginning.

The women bond over feeling inadequate, both understanding that there's no handbook for their lives the way they anticipated.

Harriet aptly shares with Elizabeth that motherhood is an experiment of its own sort, with no controlled variables for Elizabeth to grasp onto.

Lessons In Chemistry Season 1 Episode 3 introduced viewers to the idea that Harriet's husband would return from his deployment soon. This episode sees that through.

After Elizabeth and Harriet have time to bond as friends, Harriet's husband, Charlie Sloane, returns from his deployment, surprising his wife and kids.

Charlie's surprise return turns into a surprise gathering with the neighborhood, including Elizabeth, joining in.

Though Charlie seems happy to be home, it's clear that Harriet is ready to take some time for herself after carrying their household on her shoulders alone.

Harriet tells Charlie she'll be taking the BAR exam soon, asserting that nothing will change her mind as it's time for her to do something for herself.

While things have calmed down for Elizabeth and Mad at home, her work life has gotten tremendously stressful.

Elizabeth, fired from Hastings when she became visibly pregnant in Lessons In Chemistry Season 1 Episode 3, needed a way to earn her own income. 

Rather than trying to return to a lab, Elizabeth begins going over other chemist's experiments, pointing out mistakes and charging them for her knowledge,

In one of her sessions with a Hastings chemist, she learns that Dr. Donatti and Dr. Horowitz have been replicating her experiments with Calvin.

Elizabeth storms Hastings, telling both chemists off. Dr. Donatti tells her they've won the Remsen grant with her research, and Elizabeth vows to improve it further out of spite.

Still building her lab, Elizabeth takes things into her own hands.

She impersonates Fran Frask, the stiff secretary she's dealt with at Hastings for years, to purchase a massive order of lab equipment to be sent to her home.

As viewers, we get to see Elizabeth's kitchen lab take shape. It's perfect for her, suitable for cooking scientifically and performing high-level chemistry experiments.

While the series works hard to ensure that Elizabeth is shown doing well for herself, we see her subconscious hallucinating Calvin in these quiet moments throughout the episode.

Lessons In Chemistry Season 1 Episode 4 does a great job incorporating Lewis Pullman's charming Calvin seamlessly.

The Calvin we see as the audience is a quieter version of the character, a loving presence that Elizabeth talks to in her most challenging moments.

She sits down with the hallucinated Calvin toward the end of the episode and explains why we've seen him acting differently; he's a fixture of her memory rather than an apparition.

Elizabeth explains that she doesn't always know what Calvin would say or do when imagining him. She loves him, but she wishes she knew more about him.

The longing present between Larson and Pullman is palpable as two people whose deep connection was agonizingly ripped away at a critical moment.

Lessons In Chemistry Season 1 Episode 4 builds on what the audience has seen and plants seeds of what's to come.

As part of the non-linear timeline the series plays with, moments of the future are peppered throughout the episode, showing how Elizabeth's future TV series comes to be.

With an exciting look at how Mad Zott grows up, Elizabeth is seen in the future giving another parent a talking-to about feeding his child appropriately after discovering Mad has been giving her lunches away.

As the audience, we're aware Elizabeth ultimately accepts, but she shrugs off the initial offers for her own cooking series.

What Lessons In Chemistry will fill in as we continue, hopefully, is how we get from a stand-offish Elizabeth to a cultural phenomenon of her own making.

Cher Thompson is a staff writer for TV Fanatic. Follow her on X.