" May I ask you a question? If you have to hold your breath too long, what is it that makes you desperate to breathe again?” “I’m running out of oxygen, I guess.” “That’s the interesting fact. It isn’t the absence of oxygen. It’s the presence of carbon dioxide. Kind of the same thing, but not exactly. The point is, you could suck up any kind of gas, and as long as it wasn’t carbon dioxide, your brain would be happy. You could have a chest full of nitrogen, no oxygen at all, about to kill you stone dead, and your lungs would say, hey man, we’re cool, no carbon dioxide here, no need for us to start pumping again until we see some. Which they never will, because you’ll never breathe again. Because you’ll never need to. Because you have no carbon dioxide. And so on. So those folks started sniffing nitrogen, but you have to go to the welding shop and the cylinders are too heavy to lift, so then they tried helium from the balloon store, but you needed masks and tubes, and the whole thing still looks weird, so in the end most folks won’t be satisfied with anything less than the old-fashioned bottle of pills and the glass of scotch. Exactly like it used to be. Except it can’t be anymore. Those pills were most likely either Nembutal or Seconal, and both of those substances are tightly controlled now. There’s no way to get them. Except illegally, of course, way down where no one can see you. There are sources. The holy grail. Most of the offers are scams, naturally. Powdered Nembutal from China, and so on. Dissolve in water or fruit juice. Maybe eight or nine hundred bucks for a lethal dose. Some poor desperate soul takes the cash to MoneyGram and sends it off, and then waits at home, anxious and tormented, and never sees any powdered Nembutal from China, because there never was any. The powder in the on-line photograph was talc, and the prescription bottle was for something else entirely. Which I felt was a new low, in the end. They’re preying on the last hopes of suicidal people. "
― Lee Child , Make Me (Jack Reacher, #20)