Dinah, the daughter of Leah and Jacob, heads out to see the other women of the territory. While she's out, Shechem rapes her.
Jacob and his sons are naturally very upset. Men are supposed to protect their women and not doing so implies some serious dishonor.
Hamor suggests that Jacob's sons intermarry with the Hivites. We already know what Israel's clan tends to think about intermarriage (check out 24:2-4; 26:34-35; 27:46; 28:1-9), so Jacob's sons answer Hamor and Shechem dishonestly.
They want revenge for the way Shechem treated their sister.
They claim that they cannot give their sister to Shechem in marriage because he's uncircumcised.
Jacob's sons offer a condition. If all the males among Hamor and Shechem's clan get circumcised, then they can all intermarry.
Hamor and Shechem agree to the deal. Now all they have to do is sell it to the rest of the guys in the city. Not so easy, but they get the job done.
Surprise twist! Simeon and Levi, Dinah's brothers, go to the city and slaughter all the men, including Hamor and Shechem, while they're still recovering from the circumcision. The other brothers loot the city.
And now for the million-dollar question: who has the moral high ground here?