Geoff Plunkett is a retired historian and investigative researcher whose work has reshaped the understanding of some of Australia's darkest chapters. He wrote the official histories of Australia's involvement in chemical weapons, research that led to the discovery of hundreds of lethal phosgene bombs at the former chemical warfare headquarters at Marrangaroo, near Sydney.

He has authored numerous books across history and true crime, including an account of Australia's deadliest building fire. His true crime writing has had a tangible real-world impact. Death Row at Truro was shortlisted for the Ned Kelly True Crime Book Award, and The Whiskey Au Go Go Massacre contributed to the Queensland State Coroner reopening the investigation into the 1973 arson murders.

Geoff's work has featured in major Australian newspapers and on radio and television. In 2025, his investigative research led to legal proceedings that resulted in a mass-killing serial arsonist, later revealed to be a sexual predator, being returned to prison for perjury. His forthcoming book, The Burning Desire, tells that story.

Author lives in Sydney, Australia.