It's unfair to say Heath's life has gone to shit, because it's pretty much been shit since the day he was born. His abusive father left when he was young, and his mother and brother have never 'forgiven' him (because, of course, they say it's his fault). With no support at home or school, Heath turns to the other outcasts in his neighborhood: stoners, drug dealers, dropouts, burnouts, ravers, goths, and everyone else that doesn't quite fit in with their respective groups.
But then, one day, after being reported a runaway, Heath is arrested. He suffers a mental break at the thought of going home, but, luckily, he's a young white boy, so rather than locking him up, the cops bring in a trained psychiatrist to evaluate him, and she realizes: Heath isn't an asshole kid, he's acting out because he's suffering. He clearly has PTSD and potentially the sprouts of antisocial personality disorder, and there are lots of other maybes that need to be checked out.
So Heath is taken away from his family and put in a residential treatment center. And even though the kids here are weird and different from the ones he usually hangs out with, maybe he can finally make a connection with someone, for the first time in his life.
cw: smoking, drug experimentation, hiv mention, violence, verbal and physical abuse of a child (13 year old), animal cruelty (maybe??? he yells at and pushes a cat), mention of sexual assault, psychiatric hospital/residential treatment center, psychiatric meds, panic attacks, ptsd, flashbacks, cursing, implied anorexia, mentions of suicide attempts