It seems reasonable to think that one day, maybe soon, there won't be enough oil in the ground to satisfy world demands. This book tries to flesh out that idea somewhat. It's all very plausable in principle, but they just discovered an off-shore oilfield in Brazil which is purported to be as large as current Saudi reserves. Also, other known reserves, including the protected regions in Alaska, have not been tapped into, and oil is now around $2/gallon. The book notes that oil has the most "energy density" of all known fuel sources (which is why we don't have, for example, solar powered jet fighter planes), but seems to hold out little hope that technology will not be able to address this. The book makes no mention whatsoever of the countless times the "seven sisters" oil cabal has sabotaged the development of alternative energy sources. Author Deffeyes also downplays all the potential energy conservation measures which can be taken to stretch out the functional life of our current supply. Furthermore, the needlessly urgent tone of the book injects an unwanted emotional element to what ought to be a dispassionate, reasoned arguement. For context, also read "Report from Iron Mountain" by Leonard C Lewin.