_Two go in, and one comes out_. That is the way it’s been for the last two hundred years. Ever since the monsters took over the world, maintaining a low population of humans so they will not be overthrown.

On one’s 18th birthday, when there days of adolescence are behind them, they enter the dark tunnels up in the Mountains. There are only three entrances; one for you, one for your opponent, and one for a way out. As soon as you enter, the first two entrances are barricaded, making it impossible to escape back where you started.

The only way out is to face the monsters inside the cave, and be the first to exit—because once one living thing makes it through the last exit, it closes in for three weeks until the next players arrive.

_Two go in, and one comes out. _Unless, you change the system, unless you choose to sacrifice yourself and survive the three weeks in the dark. The only thing is, no one knows what happens when all the exits are completely closed—when the doors are locked. Because no one has ever been seen again after that.

But, maybe somehow, I can change that. I _have _to. Because, me and my twin sister are destined to arrive at the tunnels in a week, and will enter the game at the same time. And she _has _to make it out.

But will I?