My wife was answering a friend's question and I made some notes addressing what our doctrine says about an individual who died after receiving the gospel covenants, but then falling into serious moral transgression and subsequently dying while in that state and in particularly what we know about them in the spirit world.
The short answer Diane came up with is probably the best answer: the doctrine of Restoration found in Alma, namely, you cannot be restored from wickedness to happiness. Wickedness never was happiness.
More detail doesn't change that. The judgement bar isn't supposed to be a surprise test. Heavenly Father lets us know on what conditions he will give out different judgments because he wants us to receive a good judgement. So he tells us all about it in advance. I know that some people get all flustered and upset because you are judging if you say that adulterers are going to hell unless they repent just because the scriptures say as much. But the truth is that like Amulek we cannot deny his word - if he says such and such is what happens to adulterers, liars, and whoremongers we have no right to deny such is the case. Our answer should be no different than Amulek's:
Alma 11:36 Now Amulek saith again unto him: Behold thou hast lied, for thou sayest that I spake as though I had authority to command God because I said he shall not save his people in their sins.
37 And I say unto you again that he cannot save them in their sins; for I cannot deny his word, and he hath said that no unclean thing can inherit the kingdom of heaven; therefore, how can ye be saved, except ye inherit the kingdom of heaven? Therefore, ye cannot be saved in your sins.
If you want more detail about the spirit world just out of pure interest you need to realize some things.
Most particularly, the spirit world is NOT where we return to live with Heavenly Father and Christ. Alma says they return to that God who gave them life, but as Brigham Young points out, that isn't meant to mean they return to where God dwells, and in fact they are in the presence of God in the spirit world in about the same sense we are.
The fact that the spirit world isn't where the Father and the Son dwell, and is therefore not the celestial kingdom we are promised to be rewarded with is in all sorts of scriptures, if just not always spelled out:
1) Both Joseph Smith and Brigham Young said the spirit world is here on this earth
2) D&C 130 points out that the place God dwells is not like this earth but is a giant urim and thummim
3) Christ appears in the spirit world but afterward says to Mary that he has not yet ascended to his Father. By the way, it is also interesting htere that Christ's appearance in the spirit world sounds like an extraordinary event, not like something that was generally the case there any more than it is here. By the way, his appearance there to Adam and his posterity should be compared to his appearance in mortality to Adam and his posterity at Adam-ondi-Ahman.
There is a Brigham Young talk that gives more detail about the spirit world than any other writing I am familiar with including D&C 138, which focuses on the Savior's visit to the spirit world after his death. You can find a lot the relevant content at:
If you read Brigham Young's talk you will notice that the division of the spirit world into spirit prison and spirit paradise is the same division that exists here. It is not a division of physical location as we often imagine it. In fact, in Lehi's dream the same division between wicked and righteous is portrayed as existing here in mortality with a great gulf dividing them. The division portayed in Lehi's dream is very real and is the same division that exists in the spirit world. But it isn't a division of location here in mortality any more than it is in the spirit world.