BoJack Horseman, a washed-up actor haunted by his past, struggles with his career and relationships. He's trying to be a father figure to Hollyhock, a young woman who might be his daughter. Meanwhile, his friends navigate their own chaotic lives: Princess Carolyn, a driven agent, desperately wants a family; Mr. Peanutbutter, a perpetually optimistic actor, runs for governor; and Diane, a journalist, grapples with her marriage and beliefs.

The season's core conflict revolves around BoJack's attempt to connect with Hollyhock while battling his own deep-seated self-hatred and the legacy of his troubled family. A major turning point occurs when BoJack discovers Beatrice, his mother suffering from dementia, drugged Hollyhock's coffee. This revelation, coupled with the discovery that Butterscotch, BoJack's father, is Hollyhock's biological father, shatters BoJack's understanding of his family.

The season concludes with Hollyhock distancing herself from BoJack, telling him she never had a brother, a statement that surprisingly brings him a sense of peace. Princess Carolyn, after a series of devastating personal setbacks, finds solace in a coping mechanism.

Season 4 of BoJack Horseman covers episodes 1-12. Here's everything that happened:

Season 4, Episode 1: See Mr. Peanutbutter Run - Mr. Peanutbutter's gubernatorial campaign leads to a ski race against Governor Woodchuck. Meanwhile, BoJack is nowhere to be found. Todd accidentally wins the race for Mr. Peanutbutter. The episode concludes with California in a state of political confusion and turmoil.

Season 4, Episode 2: The Old Sugarman Place - BoJack retreats to his dilapidated family home in Michigan, befriending a dragonfly named Eddie while grappling with his family's past. Flashbacks reveal the tragic story of Beatrice's brother, Crackerjack's death in WWII, and its devastating impact on their mother, Honey, leading to her lobotomy. Despite repairing the house with Eddie, BoJack has it demolished, unable to escape his inherited trauma.

Season 4, Episode 3: Hooray! Todd Episode! - Todd juggles favors for Princess Carolyn and Mr. Peanutbutter while helping Hollyhock determine if BoJack is her father. He lies to Hollyhock about the DNA results. Todd tells BoJack that they haven't spoken in a year, which has been working for him. Todd attends an asexual support group meeting.

Season 4, Episode 4: Commence Fracking - BoJack helps Hollyhock search for her mother, leading to awkward encounters with his past. Princess Carolyn and Ralph Stilton desperately try to conceive. Diane's marriage is strained by Mr. Peanutbutter's fracking activities, leading to angry sex. Hollyhock distances herself from BoJack after his callous remarks.

Season 4, Episode 5: Thoughts and Prayers - After a mass shooting impacts Courtney Portnoy's film, Princess Carolyn initiates damage control. BoJack takes Hollyhock to meet his mother, Beatrice, whose dementia has worsened; she doesn't recognize him. Diane explores gun ownership, leading to a viral blog post and stricter gun laws in California. The episode concludes with Beatrice being kicked out of her care facility and moving in with BoJack.

Season 4, Episode 6: Stupid Piece of Sh*t - BoJack Horseman grapples with an overwhelming, self-loathing internal monologue, often visualized with crude animation, after Hollyhock asks him to get milk. He instead spends the day drinking at a bar, avoiding his responsibilities. Later, BoJack, jealous of the affection his dementia-ridden mother Beatrice shows a baby doll, throws the doll over his house. After retrieving it with Mr. Peanutbutter's help, BoJack confesses his fear of hurting Hollyhock. When Hollyhock reveals she also hears a voice telling her she's worthless, BoJack, battling his own intrusive thoughts, lies and tells her it goes away, then sits with her on the deck. Princess Carolyn discovers she is pregnant.

Season 4, Episode 7: Underground - During a fundraiser at Mr. Peanutbutter's house, an earthquake caused by fracking sinks the house underground, trapping the guests. BoJack and Diane get drunk and confront their issues. Jessica Biel burns Zach Braff alive, and the survivors eat his flesh. Princess Carolyn brokers a deal with ants to escape. The episode concludes with the main characters awkwardly discussing Ethiopian food.

Season 4, Episode 8: The Judge - Hollyhock dates an intern on BoJack's new show, Felicity Huffman's Booty Academy. Princess Carolyn meets Ralph's family, facing their prejudice. Mr. Peanutbutter supports Woodchuck in the governor race. BoJack tries to sabotage Hollyhock's relationship, but ultimately gives her advice. Hollyhock decides to meet her mother, with BoJack's support.

Season 4, Episode 9: Ruthie - Told from the perspective of Princess Carolyn's supposed descendant, Ruthie, the episode chronicles a terrible day for PC: she learns she's had a miscarriage, Judah betrays her, and Ralph breaks up with her. It's revealed that "Ruthie" is a coping mechanism PC uses to get through bad days. The episode ends with PC admitting the fantasy, but finding solace in it.

Season 4, Episode 10: Lovin' That Cali Lifestyle!! - Diane leaks damaging information on Jessica Biel. Hollyhock overdoses after Beatrice spikes her coffee with weight loss pills. BoJack, enraged, moves Beatrice to a worse nursing home. In the episode's conclusion, Beatrice suddenly recognizes BoJack.

Season 4, Episode 11: Time's Arrow - The episode explores Beatrice Horseman's life through her dementia-affected memories, revealing her troubled past and how she met Butterscotch. It's revealed that Butterscotch is Hollyhock's father, making BoJack her half-brother. BoJack, driving Beatrice to a nursing home, ultimately comforts her with a fabricated memory of the lake house.

Season 4, Episode 12: What Time Is It Right Now - BoJack helps Hollyhock contact her mother and agrees to star in Princess Carolyn's show, Philbert. Diane and Mr. Peanutbutter's relationship further deteriorates when he surprises her with a "Belle Room". BoJack realizes Beatrice drugged Hollyhock's coffee to control her weight. The episode ends with Hollyhock telling BoJack she never had a brother, which makes him smile.