Mavis is immediately identifiable as a character who’s a little stuck. She wakes up in her Hello Kitty tshirt, drinks a Diet Coke breakfast, watches a lot of bad reality TV when she should be working. Maybe her stunted growth is what makes her so successful; Mavis writes a young adult series and maybe she’s a little TOO good at putting herself into that head space.

Anyway, Mavis (Charlize Theron) has a tight deadline, so she does the rational thing and focuses all of her energy on obsessing over an email sent from the current wife of her ex-boyfriend, Buddy. It’s a baby announcement. They’ve just had a baby. Mavis assumes that Buddy’s miserable, trapped in their scuzzy hometown by a wife and now a kid. So she drives to said hometown to test her theory.

Mavis is kind of pathetic and kind of unlikable, and yet we’ve all been her, at least a little. She’s 37 but hasn’t let go of her past – perhaps the last time she felt like a whole, complete person. She peaked in high school: ugh. Gross. But the good news is, when she arrives in crap hometown, she hits a wall named Matt (Patton Oswalt). She doesn’t remember him from high school – she wouldn’t, she was popular, they didn’t exactly run in the same crowds – but he provides the little voice of reason that she clearly lacks. Not that she’s going to let a little thing like reason dissuade her; she reaches out to Buddy (Patrick Wilson) and to our communal chagrin but not surprise, he responds. To his ex girlfriend. Who I’m pretty sure he knows is trouble. While he’s dealing with his wife’s breast milk.

Anyway, Charlize Theron is disturbingly good in this. Disturbingly. Even when Mavis is being so hateful we can hardly keep looking at the screen, Theron manages the all-important drop of humanity that keeps us from throwing in the towel. She finds and celebrates Mavis’ flaws. Without her, this movie could have come off as seriously bitter. Young Adult is dark and dour, but director Jason Reitman plays to Theron’s strengths and pulls off a serious mood.