God shows Amos locusts and fire coming on Israel. Amos begs for mercy and God relents.
God shows Amos a plumb line, representing His standard for judgment. It will lead to Israel's desolation.
Another prophet accuses Amos of sedition and tells him to go to Judah and not prophesy in Israel anymore. Amos replies that this wasn't his job - God called him to it. The prophet's family and land will be laid waste, "and Israel shall surely go into exile."
Because Israel "trample[s] on the needy" by ripping them off, God will bring mourning instead of rejoicing. Famine will come, not just of food, but of God's Word.
God calls for the temple to be torn down, and He will pursue sinning Israel until they are dead.
But He will re-raise David's tabernacle, and it will include Gentiles.
How this is about Jesus
John the baptizer came with locusts, speaking of fire; Jesus set the plumb line and the temple fell 40 years later.
Jesus was rejected, as Amos was.
Jesus rebukes the rich for oppressing the poor, too ("you devour widows' houses...").
Jesus prophesies the temple, torn down, He will re-raise it in 3 days!
When we are rushing into sin, we don't want to hear God's Word.
We can't wait to sin, and our sinful hearts love it (8:4-6).
Even when a nation is going down in flames for its disobedience to God, there is always hope for God to revive and restore it in the future.