Baby Ruby tells the story of Jo, a successful French lifestyle entrepreneur who is happily pregnant, awaiting the arrival of her first child. But soon after Jo welcomes baby Ruby home, something starts to feel off - even though she's assured it's all perfectly normal. Is something wrong with her? Is something wrong with Ruby? And why are the seemingly perfect neighborhood moms so desperate to befriend her? As Jo fights to protect herself and her baby, she is plunged into a waking fever dream where everyone is a threat and nothing is what it seems. At least, she must confront the truth of her own darkness and contend with the ultimate human sacrifice: the one mothers make for their children.