I did my best to relax inside what had looked, essentially, like a giant duffle bag, the dark blue canvas surface more like the home of someone's stinky hockey gear than a life-saving hyperbaric chamber.

"We use it for cancer treatments," Dr. Aberstock told me, holding my hand as he encouraged me to step into what I tried not to think of as the means to dispose easily of my body if this didn't work, my silly brain imagining being tossed into the trunk of a car and taken ...