Rose Byrne and Meghann Fahy unpack The Good Daughter's secrets

Rose Byrne and Meghann Fahy play estranged sisters bound by two violent crimes more than 20 years apart in "The Good Daughter," the six-episode Peacock series adapted by Karin Slaughter from her own bestselling novel, now streaming in full.

The show gradually exposes a Southern Gothic mystery. Two masked gunmen broke into the Quinn family's rural Georgia home, murdering the mother, Gamma (Olivia Williams), and leaving both sisters with life-altering injuries. Rather than bonding the girls, the tragedy drove them into a bitter falling-out a decade ago. Sam (Byrne) built a lucrative patent-law career in New York; Charlie (Fahy) followed their father Rusty (Brendan Gleeson) into criminal defense in the fictional hometown of Pikeville.

A school shooting pulls Sam back. Charlie witnesses the attack that kills principal Douglas Pinkman (Kovar McClure) and a young student; Rusty is badly injured taking the suspect's case; and Sam, with little defense experience, reluctantly represents Kelly Wilson (Shayna Benardo), the pregnant teen who allegedly confessed.

What does the finale reveal?

Sam, with Charlie and Charlie's estranged husband Ben (Michael Dorman), discovers Kelly was a pawn. Judith (Paula Malcomson), the teacher who looked after Charlie after Gamma's death, learned her husband Douglas had abused and impregnated Kelly — and expected them all to raise the child together. Judith manipulated the teen into bringing a gun to school, planning to kill Douglas and blame her. When Kelly hesitated, Judith seized the weapon, executed Douglas and accidentally killed another child in the struggle.

The shooting also resurfaces the truth about Gamma's murder. Charlie had been sexually assaulted by Zach Culpepper, one of Rusty's most dangerous clients. The home invasion was orchestrated by Mason "Huck" Huckabee (Jake McDorman), with whom Charlie had a one-night stand shortly before the shooting in episode one. Charlie had accused the wrong man — Zack's brother Daniel — and that man was killed.

How do the actors read the sisters?

The estrangement drew Byrne in. "She had such fury and anger, which she speaks about in the show and in the book a lot," Byrne said of Sam, "her coming to terms with her anger toward her father and his decisions that led them to this tragedy."

Fahy saw a wider frame. "When you zoom out, it really is the story of confronting your grief and your trauma and the things that keep us at an arm's length from the people that we love," she said. "It tells a story of coming out the other side of that stronger."

Byrne traced Sam's flight from Pikeville to her mother's voice: "You have to leave. This town is corrupt. It's rigged." Fahy argued Charlie stayed to "rewrite the story or to take control of elements of the story that she didn't feel that she had."

Both sisters entered law despite the damage their father's work caused. Fahy noted the intellectually driven household — Gamma teaching the girls, even coaching Sam on landing a profanity. Byrne stressed Sam's affection for patent law's dry specificity. Fahy added: "For all of his faults, he protected her when she needed him to. He kept the secret that she asked him to."

Byrne called Sam's lack of compassion for her sister "a great flaw in the character." Fahy said Charlie's realization about Judith — who had taken her in after the assault — carried "a real, real sadness and heartbreak." She said confronting the buried trauma "ultimately allows her to come face to face with her truth," which she shares with Ben.

Why a Guns N' Roses cover?

Director Steph Green asked Fahy to record a stripped-down cover of "Sweet Child O' Mine" for episode five, in which the sisters grieve Rusty's death and uncover evidence of Huck's involvement. "Some of the words, especially in the first verse, could be Charlie singing to Sam," Fahy said Green felt. The ending mirrors episode one, with Charlie calling for her sister in the same doorway.

Will there be a second season?

Slaughter wrote a digital-short prequel, "Last Breath." Byrne didn't know of it. Fahy said the show "felt complete," though Charlie remains "one of my most cherished characters." Byrne was noncommittal: "'Anything can happen' is really my motto now in this business." She added, "it feels like the story we were meant to tell was the one we've told."

Post-finale, Charlie and Ben move to Atlanta and Sam presumably returns to New York. Byrne joked the sisters should "talk about the weather for a few weeks." Fahy praised Ben's patience: "He's loving her through it while also having his own boundary." What changes for the Quinns is a healthier distance — the question the actors leave open is whether Peacock lets them return.