Chapters 16-18

Chapter 16: Believing themselves to be close to freedom now, Huck begins to feel guilty for having helped Jim escape. Southern society has taught him that freeing a slave is a sin, and Huck starts to worry that he will go to hell.
Being forced to postpone these thoughts for later, however, Huck is confronted by men who are looking for fugitive slaves. Wanting to search the raft for the slaves, the men begin to row out to it. Huck, however, ingeniously dissuades the men from such action by telling them that his father is onboard and has smallpox. Instead of helping, the men give Huck some money in charity.
Later, now night, Huck and Jim jump overboard and are separated when a much larger vessel cuts their little raft into two pieces. Huck nearly drowns, but manages to reach shore, not having heard any sign of Jim.
Chapter 17: Now on land, Huck walks a few paces before he hears a male voice yelling at him from a nearby house window. Apparently he has reached the Grangerford family headquarters. When asked who he is, Huck tells the man that his name is George Jackson and that he has just fallen off the steamboat. Taking him inside, the man examines Huck by candlelight, convinced that he isn't a Shepherdson, the name of the family with which the Grangerfords are feuding.
The Grangerford family takes Huck in, and he admits that they were really nice. The ironic thing is, despite their obsession with feuding, the family seems to be very religious. Twain obviously uses this to further his indictment of religion.
Chapter 18: Huck's education continues. He learns that the Grangerford family is practically part of the aristocracy. The other competing aristocracy in town seems to be the Shepherdsons. The families are feuding, Huck is told, because of some dispute that happened many years ago. When he asks what the nature of the dispute was, no one knows. All of this seems quite ridiculous to Huck.
Soon word reaches the house that Miss Sophia, the beautiful daughter of the household, has run away to elope with a young man from the Shepherdson family. This immediately causes all the men of the house to fetch their guns and prepare for battle. Traveling with Buck, Huck himself sees the bloodshed first-hand. All of it, however, makes him sick to his stomach, especially when he sees Buck killed.
Luckily, he meets Jim in the woods, and the two of them run back towards the river, away from the senseless feuding.