The Case of the Peculiar Pink Fan (Enola Holmes, #4)2008
by Nancy Springer
When Enola encounters a familiar young lady carrying a paper fan, she is sent immediately into action--for the girl is her old friend Lady Cecily, and the peculiar pink fan signals that Cecily is in terrible peril!
But what, exactly, is the matter? And how can Enola help? After following many clues that lead nowhere, Enola at last discovers that young Lady Cecily is being held prisoner in an abysmal orphanage, and if she isn't rescued, she'll soon be forced into a miserable marriage!
This complicated case has Mycroft, Sherlock and Enola running into each other (literally) all over London. If Enola, in order to save Lady Cecily, joins forces with the brothers she has fought desperately to elude, she risks her freedom...yet, if she does not enlist Sherlock's help, Lady Cecily could be...