Breathe

Trapped and running out of air, five must die if anyone is going to survive.

Zoey is an ambitious young botanist and it looks like joining the founding crew of the first human colony beyond the asteroid belt is going to pay off, until Karl's insane little scheme to win her affections backfires spectacularly. Not only does he accidentally expose her affair with the base commander, he has unleashed a chain of events that leads to the catastrophic failure of the station, trapping nine people in an emergency refuge that can only recycle enough aire for four.

The maths are simple, five of them must die if anyone is to survive...