Radon is a naturally-occurring radioactive gas that we are warned about in our basements. We know the dangers of radiation, which was driven home forcefully after Hiroshima and during the arms race. But there are people who believe that exposure to radon can be beneficial in curing what ails ya, including chronic pain. There are places that people go to and pay good money to be exposed to radon. Radon therapy seems to help some people, but is it a miracle, a placebo, or a matter of faith? Tom Scott visits the radonstollen (radon tunnel) in Bad Kreuznach, Germany. The unique feature of this tunnel/pain clinic/spa is that the radon can be turned on or off! It sounds like the perfect place to propose a double-blind study on the effects of radon, but that probably won't happen.