Preston primarily follows Peter Jahrling, DA Henderson, Lisa Hensley, and several others who played critical roles in the eradication of smallpox and containment of other lethal microorganisms. He follows them from American top-secret laboratories to Russian ones and recounts the private conversations they have in both. Besides illustrating their roles in the fight against modern biological warfare, he also delves into their personal lives, revealing their driving beliefs and distinct personalities. However, Preston recounts their experiences with such clarity and confidence that I couldn't help but feel that the book was crossing over into the realm of literary sensation. Furthermore, by focusing on a nationally-distinct set of individuals, the book manifests a twinge of political bias.
From the US's discovery that the Russian Zagorsk Virological Center produced 20 tons of weapons-grade smallpox to Lisa Hensley's slipping scissor incident while working with the ebola virus, events Preston includes in "Demon" consistently emanate the tension between the world's polarized political environment at the times they took place. This tension sustains in "Demon" at a consistently high level from beginning when the dangers of biological warfare are introduced to the 'resolution' at the end. As a result however, hard facts and figures of the often gets lost amidst the suspense, weakening the credibility of "Demon's" categorization as non-fiction.
Ultimately, I felt like I was reading a Tom Clancy novel rather than a historical non-fiction. Whether this is a strength or weakness of "Demon" depends on readers' preferences.