This case study is used to teach undergraduate students about hydraulic fracturing (hydrofracking), a controversial method for extracting methane from shale. The controversy arises from claims that chemicals used in the fracking process and the methane itself find their way into drinking water and are also sometimes found at dangerous levels in the air. The case study begins in a college chemistry class where a student inquires about a news item he saw about residents setting their tap water on fire. The instructor uses this as an opportunity for the students to research hydrofracking and natural gas, and then integrate these topics into their present study of isotopes. The class first examines what isotopes are by using a guided inquiry based activity. The students then learn how mass spectrometry, which uses the principles just learned about isotopes, is employed to determine the source of methane in contaminated wells. This case study is designed for freshman chemistry students and students in environmental studies.