Hersh is eventually diagnosed as bipolar and prescribed lithium, which makes her swollen and shaky and broken out. A doctor describes the experience of being properly treated for the disease as being reborn. But the larger question it leaves her with, like so many people who seek medication for mental health issues, is, "What's left? What's 'me'? Anything?" She must sort through the traits she had seen as parts of her personality—the need to swim every day or the ability to write music—to figure out which are just elaborate coping mechanisms for her mental highs and lows, and which are really her. This is not far from the kind of musing about identity common to most teens, but it's exaggerated in light of the bipolar disorder.
None of this proves to be enough to break up the band and eventually, after moving to Boston and recording a demo, they sign to the legendary British record label 4AD. Hersh's phone conversations with the plummy label head Ivo Watts-Russell are one of the book's highlights. He will take her call at 4 a.m. while she's having a difficult time recording vocals for the album and distracts her with stories about old men feeding birds in the park: "He's got like a dozen pigeons on him. And these are filthy London pigeons, mind you."
Just as things seem to be taking shape and taking off, Hersh becomes pregnant. (She doesn't say by whom; she merely explains that "some little boys like rat girls. Not many, but a few.") But Hersh continues to play live, yell at journalists who ask sexist questions, and records the band's first album while having very little clue how she's going to navigate motherhood. Besides, she decides that "babies are so punk rock: bald and drooling, yelling and grinning, learning how to work their new spaceships made of bone, muscle and skin." It's probably her invincible adolescent mindset that helps her, in a way; she seems to have no real idea what she's up against. She knows that she doesn't want to be like the staid yuppie couples in her birthing class; instead, she and the band make a group decision to figure it out on the fly.
Rat Girl stops just as everything seems to be starting—the album is about to be finished, she gives birth. Hersh will not pander for our sympathy or satisfy our need to hear how things turn out. Her story is about what it's like to live and to think as a teenage girl, not a book about what happens when she finally grows up.