Articles referencing to this book: Grace Pett's Combustion Mary Clues' Fiery Death

This book is a classic in the realm of anomalous studies; it helped re-establish Spontaneous Human Combustion [to be referred to as "SHC" from here on] as a viable twentieth-century mystery to ponder, long after scientific studies at the end of the 1800's discredited it in the public mind.
Harrison's book, however, is not just about cases of what can be classfied as SHC (when humans appear to self-ignite from inside their bodies); he also offers up a potpourri of other fire-related mysteries -- poltergeist fires, the Tunguska fireball of 1908, and people who could apparently handle flames without harm, for instance -- all of which, he tries to assert, is somehow related simply because they are mysterious and involve fire.
The weak point of the book, in fact, is his attempt to explain everything, and in some pretty vague ways. However, it's strong points are that it introduced many now-classic cases of SHC to the world, as well as documenting a huge number of extremely old texts in his bibliography about all forms of ancient anomalies. It's a good read, and the SHC starting point for almost every author that followed Harrison until the publication of Larry Arnold's massive tome, Ablaze!.