This book does not start off strong. We learn too much about Baruch's genealogy, and that he's writing this in Babylon at the same time as the Chaldeans sacked Jerusalem. This book is a transcription of a sermon he gave to someone called Jechonias, the son of Joachim, the king of Juda, and a bunch of nobles and commoners. When they heard the sermon, and we're up to verse 6 with nary a word, they wept and collected money to send to Joachim for rebuilding. Apparently Joachim was left behind while everyone else was carried off to Babylon, where they were allowed to continue to write letters and send money and temple decor. Anyway, in their letter, they instruct Joachim to make sacrifices on their behalf and pray for the life of king Nabuchodonosor of Babylon and crown prince Balthasar. They also want Joachim to read the book aloud. They admit to sinning and disobeying god ever since they left Egypt, which is why they're now in Babylon.
So they don't really blame god for making their lives miserable by sending plagues and causing them to eat their own children or selling them into slavery. Not so different to these guys today.
And have they learned from all this? Why, no. They continue to sin. But now they want forgiveness. They know they've been told they need to stay in Babylon or god will cause to cease out of the cities of Juda, and from without Jerusalem, the voice of mirth, and the voice of joy, the voice of the bridegroom, and the voice of the bride (v. 23) And you know what happens when you piss off a bride! But it seems something has happened to the bones of their ancestors: they've been cast out onto the ground, because this book is basically a zombie saga, and the temple ruined.
Anyway, they want god to listen to them so they don't end up assimilating into Babylonian society and disappearing as a people. And also, god promised to send them back to Israel at some point and they'd like that to be now, please.