Slowly, Susannah opens her eyes to darkness and silence. She wonders where she is and thinks her scalp itches. Immediately, she understands that she needs to leave this place. As she tries to move off of the bed, she realizes there's something restraining her. Susannah looks out the window and feels relief to see that there are taxis outside—she's in New York City. This relief is short-lived, however, when she sees the “purple lady” staring at her.
This passage is typed in italics. Cahalan will later make it clear that this signifies that this is a hallucination, or something that didn't actually happen. This introduces the idea that Susannah is an unreliable narrator, and one who's driven very much by quickly roiling emotions.
Susannah yells at the purple lady for help, and the lady tries to soothe Susannah. She has a Jamaican accent, and Susannah wonders if this is Sybil, her childhood babysitter, back to care for her. The purple lady explains that Susannah is in the hospital, and slowly begins to undo the restraint. Susannah lifts a hand to itch her scalp and discovers she's wearing a cotton hat. Incensed, Susannah rips off the hat and finds that there's a web of wires under the hat. She begins to pull off the wires and notices an orange band on her wrist that says, "FLIGHT RISK."
Connecting the purple lady to Sybil shows Susannah using memory to momentarily find comfort in a scary and confusing situation. The fact that Susannah cannot soothe herself and calm down is indicative of how ill she is, and of how not “herself” she is at this point. This all sets the stage to help the reader understand where exactly Susannah is headed in the lead-up to her hospitalization.