In 2009, filmmaker Josh Fox learned his land was on top of the Marcellus Shale, a giant reservoir of natural gas that stretches across huge stretches of the northeast United States, and that he would be paid to lease his land for natural gas extraction. Fox documented his cross-country trek to find out if the controversial process of hydraulic fracturing (or fracking) is actually safe. What he unearthed was a discovery about a practice that is understudied...