We hope you're not afraid of the dark, because there's a lot of it in this book. We're guessing the title, In Darkness, could have told you that. We're pretty sure the literal meaning of the title is also pretty obvious: Shorty is pinned down underneath a bunch of rubble and can't see anything around him. He tells us, "I was born in darkness, and I will die in darkness. I can't even see the crack of light anymore, cos it was blocked by the thing that fell down" (21.3). So yeah, lots of darkness going on here.
Then there's the deeper, more figurative meaning. It's not just that Shorty needs a flashlight, but that he doesn't know how to get out of his current situation. He's dealing with the gang, death of his dad, and his lost sister. We can tell that Shorty's whole life has been lived in darkness—life in the Site offers little more than hopelessness, drugs, and violence.
The earthquake makes Shorty's plight concrete for us. As he waits to be rescued in complete darkness, we can't help but notice how similar that is to his real life situation. Shorty needs to be rescued from his dark and troubled life, too. It's a metaphor, but it really happened.