I think I’ve just seen a man running after a girl in the woods.
-- Deborah Cooper (The Day of the Disappearance (Saturday, August 30, 1975))

Importance: The beginning of the novel surrounds the emergency call made by Deborah Cooper to the police after she sees Nola Kellergan being chased in the woods. This paves the way for the novel, as Nola’s disappearance will become central to Marcus’s own book about the disappearance. It will also bring negative national attention to Marcus’s mentor, Harry Quebert.

I’m giving you six months. You have until the end of June.
-- Roy Barnaski (Chapter 31)

Importance: The head of Schmid and Hanson, Roy Barnaski, grows impatient with Marcus having taken so long to begin working on another book. Roy gives Marcus the ultimatum of writing or losing his contract. This is what compels Marcus to call Harry for help. Then, Harry invites Marcus to his home in Somerset.

That was all I knew about Nola Kellergan… It...
-- Marcus (Chapter 31)