After Nephi and his brothers got back from their women-hunting mission to Jerusalem, it came to pass that Lehi had another dream -- that is he dreamed a dream; or, in other words, he had seen a vision.
And it came to pass that while my father tarried in the wilderness he spake unto us, saying: Behold, I have dreamed a dream; or, in other words, I have seen a vision.1 Nephi 8:2
(The dream that Lehi had was nearly identical to Joseph Smith, Sr.'s dream 2400 years later, before Joseph Smith, Jr. "translated" the Book of Mormon. But I'm sure that was just a coincidence.)
Lehi dreamed about tree with fruit that could make you happy if you ate it (or smoked it?).
And it came to pass that I beheld a tree, whose fruit was desirable to make one happy.1 Nephi 8:10
Lehi partook of the fruit thereof, and it was the sweetest thing he'd ever tasted, and was whiter than anything he'd ever seen before. (Being white is the best thing a thing can be in the Book of Mormon.)
And it came to pass that I did go forth and partake of the fruit thereof; and I beheld that it was most sweet, above all that I ever before tasted. Yea, and I beheld that the fruit thereof was white, to exceed all the whiteness that I had ever seen. 1 Nephi 8:11
And it made him exceedingly happy, happier than he'd ever been before. He was so darned happy he could hardly stand it. So he wanted his family to eat from the happy tree, too.
And as I partook of the fruit thereof it filled my soul with exceedingly great joy; wherefore, I began to be desirous that my family should partake of it also; for I knew that it was desirable above all other fruit.1 Nephi 8:12
So Lehi cast his eyes round about until he discovered his family.
And as I cast my eyes round about, that perhaps I might discover my family also, I beheld a river of water; and it ran along, and it was near the tree of which I was partaking the fruit.1 Nephi 8:13
Lehi told his family to eat the happy fruit, and the good members of his family (Nephi, Sariah, and Sam) ate it.
And ... I beheld your mother Sariah, and Sam, and Nephi; and they stood as if they knew not whither they should go. And it came to pass that I beckoned unto them; and I also did say unto them with a loud voice that they should come unto me, and partake of the fruit, which was desirable above all other fruit. And it came to pass that they did come unto me and partake of the fruit also. 1 Nephi 8:14-16
After the good guys ate the good fruit, Lehi cast his eyes about again until he saw Laman and Lemuel. He told them to eat the fruit, but they wouldn't do it (because they were bad).
And it came to pass that I was desirous that Laman and Lemuel should come and partake of the fruit also; wherefore, I cast mine eyes towards the head of the river, that perhaps I might see them. And it came to pass that I saw them, but they would not come unto me and partake of the fruit. 1 Nephi 8:17-18
Lehi saw an iron rod along the side of the river that people clung to as they traveled towards the happy tree.
In the background there was a mist of darkness; yea, even an exceedingly great mist of darkness that lots of people got lost in.
And it came to pass that there arose a mist of darkness; yea, even an exceedingly great mist of darkness, insomuch that they who had commenced in the path did lose their way, that they wandered off and were lost. 1 Nephi 8:23
But some managed to find the happy-fruit tree by hanging on to the rod of iron.
And it came to pass that I beheld others pressing forward, and they came forth and caught hold of the end of the rod of iron; and they did press forward through the mist of darkness, clinging to the rod of iron, even until they did come forth and partake of the fruit of the tree.1 Nephi 8:24
But after partaking of the happy fruit, the people cast their eyes about like they were ashamed or something.
And after they had partaken of the fruit of the tree they did cast their eyes about as if they were ashamed. 1 Nephi 8:25
Then Lehi cast his eyes about again and saw a big building floating in the air.
And I also cast my eyes round about, and beheld, on the other side of the river of water, a great and spacious building; and it stood as it were in the air, high above the earth.1 Nephi 8:26
The building was filled with people that were looking down and pointing and laughing at the people eating the happy fruit.
And it was filled with people, both old and young, both male and female; and their manner of dress was exceedingly fine; and they were in the attitude of mocking and pointing their fingers towards those who had come at and were partaking of the fruit.1 Nephi 8:27
Then the people who were ashamed after eating the happy fruit crawled off into the darkness and got lost.
And after they had tasted of the fruit they were ashamed, because of those that were scoffing at them; and they fell away into forbidden paths and were lost.1 Nephi 8:28
Some of the ashamed fruit-eaters made it to the big building, but others drowned.
And he also saw other multitudes feeling their way towards that great and spacious building. And it came to pass that many were drowned in the depths of the fountain; and many were lost from his view, wandering in strange roads. 1 Nephi 8:31-32
Those that made it into the big building in the sky began pointing the finger of scorn at the happy fruit eaters below.
And great was the multitude that did enter into that strange building. And after they did enter into that building they did point the finger of scorn at me and those that were partaking of the fruit also; but we heeded them not. 1 Nephi 8:33
Here's what the whole thing looked like.