Just read it.

What's beyond the gate in Chicago? The Bureau of course... Right? But what if that wasn't the case? What if beyond the gate there was much worse. What if the message from Edith Prior... Was a dead end? And beyond the gate is Panem, a place much worse than Chicago. What happens when Snow, the man who makes Jeanine Matthews look like a saint, decides that these strangers from Chicago that he's never met, aren't safe either? And two of them are Reaped for The Hunger Games the same way as it is in the Districts. It doesn't matter if Katniss knows the truth about where they come from. It doesn't matter that these 'Strangers' were placed in District 12, or that she knows the three people who were also Reaped. The Girl On Fire has to get home to her sister. But the Number Boy has someone to get home to too. What happens when the Boy With Four Fears meets The Girl On Fire? How far would they both stoop to get back home to the person they love?