The Demon in the Freezer is a non-fiction book about the metaphorical "demon" referring to biological weapons and the US government's measures to counter them. It was published in 2002 and was written by journalist Richard Preston.
The book primarily talks about smallpox and anthrax, two of the main biological threats that have plagued the United States. The metaphor of the "freezer" refers to the samples of the smallpox virus that are still being kept in labs in the United States and Russia.
Preston's account mostly addresses the Smallpox Eradication Program that the US government undertook between 1967 to 1980. It has, however, received mixed reviews by critics who called the style of writing "awkward."