Recently I've read through a few books on sideshows and freaks (sort of side resarch for my next novel). Most are skimming histories of people and events. Adams has created something altogether different. Drawing on poststructuralist techniques, Barthes, theories of the leisure class, and methodologies of deconstructing narratives of the other (what "freak" would do all this!!??) she pursues the notion of freaks from appropriated nomenclature to social constructs, to name a couple avenues. You want to understand Browning's movie, then this is the essay.
Her research drew upon many sources, often comprehensive, at other times less than complete. The problems are minor, some people in photographs or freaks who wrote about their positions are not mentioned, or a name might be missing in the index, or a photo clearly dated 1885 in the picture is listed as 1903. And on a broader level I suppose she could be faulted for falling into the same trap she critiques, that of denying her her subjects voices (kudos for mentioning Gayatri Spivak but what would she say about this?)
But don't misread my finicky carping. This is an excellent book and one I'd recommend above all others I've seen for digging into our individual and collective psychologies. Read it and learn why the freaks say, "Gooble Gobble Gooble Gobble, we will make you one of us."