This remarkable book by German physician and psychic researcher Baron von Schrenck-Notzing focuses on a series of séances, witnessed between the years 1909 and 1913, involving the French medium Eva Carrière (or Eva C). Born Marthe Béraud, Carrière changed her name in 1909 to begin her career afresh after a series of seances she held in 1905 were exposed as a fraud. Her psychic performances as Eva C gained the attention of Sir Arthur Conan Doyle who believed she was genuine, and also Harry Houdini, who was not so convinced. Another researcher who became interested in her case was Albert von Schrenck-Notzing. A series of tests he devised between the years 1909 and 1913 convinced him that Eva C was the real deal and in 1913 he published his Phenomena of Materialisation detailing the sessions and the reasons for his belief.

It has been noted that these sessions with Schrenck-Notzing verged on the pornographic. Carrière's assistant (and reported lover) Juliette Bisson would, during the course of the séance sittings with Schrenck-Notzing, introduce her finger into Carrière's vagina to ensure no "ectoplasm" had been put there beforehand. This would be followed by Carrière stripping nude at the end and demanding another full-on gynaecological exam. Whether the audience members were obliging is up for debate, but reports that Carrière would run around the séance room naked indulging in sexual activities with her audience suggests perhaps so. One can imagine that this deliberate eroticisation of the male audience might go some way to explaining the ease with which these "investigators" believed the psychic reality of the seances. A decision of fraud on their part would distance their involvement somewhat from the special and heightened context of the séances and so cast their complicity in, or at the least witnessing of, sexual activities in the sober (and more judgemental) cold light of day.

The spiritualist debunker Harry Price wrote that the photographs taken by Schrenk-Notzing, rather than proving the reality of Carrière's mediumship, in fact did just the opposite. In 1920, Carrière was investigated by the Society for Psychical Research in London. An analysis of her ectoplasm revealed it to be made of chewed paper and the ghostly faces to be cut from the French magazine Le Miroir. Back issues of the magazine matched some of Carrière's ectoplasm faces, including Woodrow Wilson, King Ferdinand of Bulgaria, and the French president Raymond Poincaré. This is something Schrenk-Notzing tries to address in his book, but without much success. A 1913 newspaper article explained how

Miss Eva prepared the heads before every séance, and endeavoured to make them unrecognizable. A clean-shaven face was decorated with a beard. Grey hairs became black curls, a broad forehead was made into a narrow one. But, in spite of all her endeavours, she could not obliterate certain characteristic lines."