While visiting the rather dull, conventional, country home of John and Anna Denman, Mr. Satterthwaite unexpectedly meets Mr. Quin on a narrow road called Harlequin's Lane behind the house. Locally, it's known as Lover's Lane. While exploring the lane, Satterthwaite meets Molly Stanwell and learns that there's to be an entertainment, a masquerade, that evening.