Breathless

From the Introduction: Things have gone wrong. You're all trapped in an air tight environment. Perhaps it was a mine collapse, or perhaps you're on a stranded submarine. You're being held hostage in a bank vault. Your escape pod is adrift in space. Rescuers have gotten in contact with you and say they can get to you in twenty-four hours, but no sooner. Unfortunately, they heard how many of you are alive in there. They've crunched the numbers. There isn't enough air to last you all that long, and nothing can change that. Well, almost nothing. Though they didn't say it, you're all thinking it. If one of you dies, you should have enough oxygen to last until you are saved. But who will it be? Who will do it? How? And how will you explain your actions once you're free?