The Letter takes place in the 1950's.  The Letter, written by Raymond, from his prison cell to his girlfrien Janis takes place over the course of one night.  Through the letter we discover the reason why Raymond is in prison, his relationship with Janis and Raymond's percived "perfect family. " 

Through the course of the letter we see Raymond's past life with his family and Janis and his current life in prison.  Through out the Letter, a Clock Tower continues booming out it's bells from 12am-6am as Raymond writes.