In a narrative, the exposition sets the initial situation before the action starts.
"The Adventure of the Cardboard Box" begins with Sherlock Holmes and Dr Watson in their Baker Street flat. Holmes is reading a newspaper article about a Miss Susan Cushing who received a yellow cardboard box in the mail, containing two human ears in salt.
An inspector from Scotland Yard, G. Lestrade, is willing to meet with Holmes to discuss his theories on the case.
