Dr. Jekyll and Mr. Hyde is referenced about halfway through the novel. According to Gemma, "Dr. Jekyll and Mr. Hyde was one of my uncle's favourite books...He thought everyone had to struggle between the good and bad parts of himself" (Livesey 225). Dr. Jekyll and Mr. Hyde was published in 1886 by Robert Louis Stevenson. According to the Encyclopaedia Britannica, "The names of Dr. Jekyll and Mr. Hyde, the two alter egos of the main character, have become shorthand for the exhibition of wildly contradictory behavior, especially between private and public selves" (Lebeau). As with Jane Eyre, The Flight of Gemma Hardy utilizes allusion in order to construct parallels. Here, Gemma Hardy makes a parallel between the alter ego she'll soon discover of Mr. Sinclair by referencing it as one of her uncle's favorite books. As the novel progresses, it even reveals the own alter egos present within herself. 

Bibliography: Lebeau, Vicky. “The Strange Case of Dr. Jekyll and Mr. Hyde.” Encyclopaedia Britannica. 1 Mar. 2019, https://www.britannica.com/topic/The-Strange-Case-of-Dr-Jekyll-and-Mr-Hyde. Accessed 31 Oct. 2019.

Livesey, Margot. The Flight of Gemma Hardy. HarperCollins, 2012.