Research on the person who allegedly punched Houdini causing his death.
The book is interesting but it's more a "research diary" than a biography of J. Gordon Whitehead. It is however interesting to read all the work that went into this research. The book could benefit with an extra chapter to summarise the life story of Whitehead.
From what I understand, this Whitehead (a Scot) was a mentally unstable man who probably had a fit and punched Houdini although this can't be proved or dis-proved.
A nice read and the only known photo of Whitehead.