Sir Arthur Conan Doyle was an ardent spiritualist, and in this book he explains his reasons why. There are many examples of apparent psychic phenomenon described in this book that Doyle absolutely believed were real. Once belief described includes how he thought that Houdini could dematerialize, and that was how he escaped from handcuffs and jail cells. Needless to say, Houdini and Conan Doyle disagreed on this subject, even though they had tremendous respect for each other. This is a fascinating read that you will enjoy.