Peacock's All Her Fault followed a mother who uncovered shocking revelations about her family after her son disappeared in plain sight - but how did the season end? Based on Andrea Mara's novel of the same name, All Her Fault began with Marissa (Sarah Snook) coming to pick up her son, Milo (Duke McCloud), from a playdate - only to find that she was tricked. The search for the 5-year-old revealed that Marissa's friend Jenny's (Dakota Fanning) nanny Carrie (Sophia Lillis) was to blame.