This is a modern fairytale, a post-apocalyptic story that, while clearly in a modern setting, partakes of the flavour and imagery of legend. Green is the conscientious adolescent who stays behind when the rest of her family (mother, father and little sister) go to the city. The city burns, the family dies, Green is left to survive alone.
She ... survives. She befriends wild things; tattoos herself, laboriously and repeatedly, with twisted ink briar-roses; cautiously re-presents herself to her neighbours as a tough, independent, and most of all solitary young woman. She's scornful of the simple rebellions of other teenagers, but finds solace in helping those in need. And she learns from those she helps: "The hawk needs to hunt, the sparrows need to fly ..."
It's never explicitly stated what the human needs, what Green herself needs: but it's in there all right. The human needs society, emotion, interaction.
The 9/11 allegory is not forced, but gradual. The cause of the city's destruction -- terrorism -- isn't immediately stated, though I think it's clear that it's not a natural disaster. But is it overt war, or not?
"... the enemy amongst us," someone tells Green, "their people, their children, died too." And Green, already within her fragile protective shell of fear and isolation, is suspicious of the newcomer who will not show his face. (Which tells us a lot about the 'enemy': that it's a visible difference, a racial difference.) It's a relief to her (and to the reader) to discover that the stranger is marked, not by Difference but by similarity; burnt and scarred, another victim.
There isn't a happy ending here, not a traditional one anyway, but there's a sense of closure, of coming through an ordeal and emerging from the thorns. Green will always be marked -- briar-roses -- by her losses and by the way she's coped with them, but by the end of the book she's ready to move on.
Green Angel is a deceptively simply novel, and not a long one. It's as much about isolation, not fitting, coping strategies as it's 'about' the aftermath of 9/11. Thought-provoking and written with clarity and compassion.