41 - Governor Gedaliah murdered. The remnant corporately kidnapped (Jeremiah presumably with them) to be taken to Ammon. Johanan rescues them and they head for Egypt.
42 - they ask Jeremiah for God's direction. He says to stay in the land - going to Egypt would be disastrous.
43 - they don't listen imputing false motives to Jeremiah. When they get to Egypt, Jeremiah prophesies that Babylon will conquer it.
44 - Jeremiah prophesies that God will destroy them for their continued idolatry. They flatly reject it, saying it was for stopping their sacrifice to the queen of heaven that they were destroyed. Jeremiah says God did it, remembering that idolatry. If they want to find out who did it, just stay in Egypt and God will destroy them.
45 - Baruch, sad to be losing so much (was he a nobleman? Jer 43:3) gets some perspective, straight from God. He's in the middle of tearing down Israel, and Baruch is looking for comforts. All he'll get is his life.