In the book Mann describes how he became a researcher investigating the temperature record of the past 1000 years and was lead author, with Raymond S. Bradley and Malcolm K. Hughes, on the 1999 reconstruction that was the first to be dubbed the hockey stick graph.

[3] Kirkus Reviews called it "an important and disturbing account" of attempts to spread doubt about climate science, and said "This blistering indictment of corporate-funded chicanery demands a wide audience.

[5] In the Geoscientist magazine of the Geological Society of London, Colin Summerhayes described Mann as "a pioneer in analysing proxy records of climate change covering the past 1,000 years" whose early work had attracted vituperative attacks but had been supported by subsequent studies, and would "heartily recommend this book for an unusually clear view of the action on the front line of climate science".

[1] Michael Marshall, environment reporter for New Scientist, commented that although other studies showed the "hockey stick" graph was essentially correct, it came under persistent attack over statistical issues that the book explains in detail, difficult reading material which "will be invaluable for anyone confused by the many claims and counterclaims found online."

She said the book was largely "score-settling with anyone who has ever doubted his integrity or work: free-market think tanks, industrialists, 'scientists for hire,' 'the corruptive influence of industry,' the 'uninformed' media and public.