Noun
(literary) A series of miserable events that will eventually lead to a happier outcome.
(religion) The Biblical story of the fall of Adam and Eve and the loss of the Garden of Eden, known theologically as the source of original sin - meaning that this loss of innocence was a fortunate fall because of the good that would come from it, that is, Christian redemption and the eventual hope of Heaven.
Source: en.wiktionary.org