What major events take place in the Custom House through Chapter 4

Rather than just repeating GradeSaver, I encourage you to check out their summary. Just scroll through Custom House. Much of the story then deals with long descriptions of the various men with whom he worked in the Custom House. General Miller, the Collector, is the oldest inhabitant, a man who maintained a stellar career in the military but who has chosen to work in the Custom House for the remainder of his years. As for the Inspector, his job was created by the man's father decades earlier, and he has held the position ever since. The Inspector is the most light-hearted of the workers, constantly laughing and talking in spite of his age. THen Chapters 1-4 primarily deal with Hester's release from prison and underlying conflicts with Chillingworth and Dimmesdale.

http://www.gradesaver.com/the-scarlet-letter/