Elspeth Spindle is the protagonist of One Dark Window, “a pretty maiden with long black hair and charcoal eyes” (51). She is the daughter of Iris Whitebeam and Erik Spindle—the former Captain of the Rowan King’s 13 Destriers (elite soldiers)—as well as the stepdaughter of Nerium and half-sister to Nya and Dimia. As the novel progresses, she becomes current Captain Ravyn Yew’s love interest and a member of his Deck-forming team. At nine, Elspeth was infected by the god-like Spirit of the Wood’s mist, but her father hid her with maternal relatives, the Hawthorns, rather than submit her to the Physicians. At her aunt Opal and uncle Tyrn’s estate, she encounters the magical Nightmare Card and absorbs the soul of its creator, the Shepherd King—or the Nightmare. For 11 years, she hides his presence in her mind.

At the beginning of the novel, Elspeth is presented as passive, forced to keep to the fringes of Blunder society for fear of revealing her infection and powers. However, her encounter with Ravyn and his team changes her, developing her self-confidence. This association with Ravyn’s team comes at a cost, as she often relies on the Nightmare‘s deteriorating power to defend herself and others.