Eventuellt The Doorkeepers av Graham Masterson?
Det äger rum i London, flera av Goodreads recensionerna omnämner alternativa realiteter och Google Books-utdrag visa resultat för "tuberkulos" och "Hooded Men".
“Well, the Hooded Men want us to believe that it's Purgatory, to discourage us from trying to visit it, and to give them an excuse for capturing and killing everybody who accidentally makes their way through."
och
How could there be another world where people went by train under the Channel and people flew to New York in three hours and there was color television and cures for tuberculosis and almost everybody was connected to >almost everybody else by computer?