Who Are The Main Characters In All Her Fault?

If you just want the short roll call from 'All Her Fault', here’s the tight list I keep thinking about: Marissa Irvine (the mother, played by Sarah Snook), Peter Irvine (her husband), Milo Irvine (their young son), Carrie Finch / Josephine Murphy (the woman connected to Milo’s disappearance), Lia Irvine (Peter’s sister), Colin Dobbs (Marissa’s friend and partner), Brian Irvine (the younger brother), Jenny Kaminski (a fellow mom involved via the playdate), and Detective Jim Alcaras (investigating the case). Those are the main players who shape every twist and reveal in the story. What stuck with me was how each character carries moral grayness — nobody is just villain or victim — which makes the mystery hit harder emotionally. I kept rewinding moments in my head after finishing it because the relationships make it linger.

I got pulled into 'All Her Fault' like someone who wandered into a neighborhood argument and couldn't look away — the characters are the reason it hooks you. The central figure is Marissa Irvine, played by sarah Snook on the screen: a wealthy, high‑functioning mom and wealth manager whose life collapses when her son goes missing. Her husband Peter Irvine (Jake Lacy) is outwardly supportive but deeply complicated; he's a commodities trader with secrets that resonate through the whole story. The missing child at the story's heart is Milo Irvine, their five‑year‑old, and his disappearance is the pivot around which everything spins. Then there’s Carrie Finch (also known as Josephine or Josie Murphy in the backstory), portrayed by Sophia Lillis: she’s the nanny/nanny‑figure whose actions are central to the mystery. Other major players include Lia Irvine (Peter’s sister), Colin Dobbs (Marissa’s best friend and business partner), Brian Irvine (Peter and Lia’s younger disabled brother), Jenny Kaminski (a fellow mom connected to Milo’s playdate), and Detective Jim Alcaras, who leads the investigation. These are listed as the main cast and characters in the series and the book that inspired it. Beyond the names, what I love about these characters is how they’re not just props for the thriller mechanics — they carry social and emotional weight. Marissa’s public life versus private panic, Peter’s quietly corrosive choices, and Josie/Carrie’s tragic spiral are all threaded with real human messiness. Colin’s gambling subplot and Lia’s struggles add layers that keep the mystery from being one‑note. The detective figure, Jim Alcaras, isn’t just a procedural device; he has his own humane angle, and even the supporting folks like Jenny and Milo’s classmates amplify the claustrophobic suburban vibe. The adaptation keeps the ensemble feel from Andrea Mara’s novel while leaning into performance moments that actors like Sarah Snook and Dakota Fanning make memorable. If you want a compact mental map: Marissa and Peter are the married couple at the center, Milo is the missing child, Carrie/Josie is the complex kidnapper/biological‑mother figure, and Colin, Lia, Brian, Jenny, and Detective Alcaras round out the core ensemble whose secrets and relationships drive the plot. I ended up caring about several of them even as the plot did some Wild turns; that mix of melodrama and real emotional stakes kept me gripped until the credits, and Snook’s performance especially stuck with me.