I was pretty surprised by where they went with all of the stuff with Adelaide's husband. I was a bit confused though, was there no anarchist group at all, or did he just make it look like they were the ones doing everything? Was he part of a bigger conspiracy or was he working alone?
It's a historical fact that William McKinley was killed by a member of an anarchist group mere days after this episode's events. Presumably Benjamin was a member of the same group, with his attack being their first try and Leon Czolgosz finishing the job four days later (which they conveniently glossed over so as not to spoil our heroes' "victory").
The business with the book being the key for the anarchists' cipher was real. Benjamin couldn't have known that Houdini would take his copy of Tom Sawyer; probably the reason he contacted Adelaide was to try to get hold of the book (which he did) so that he could decipher the code in the newspaper and learn where and when to strike. Note that Doyle saw that he had the book in his pocket at the hotel. So, yes, the anarchist group was real, and Benjamin was the one they were trying to get instructions to. His deception was his attempt to convince Adelaide that he was working undercover to stop the anarchists, rather than working with them.
Although, really, the idea of an organized group of anarchists is kind of a contradiction in terms, isn't it?
