Complex sentence: She retreats and unsuccessfully attempts to abort the self-destruct, then returns to find the Alien gone and narrowly escapes in the shuttle as the "Nostromo" and its enormous cargo is destroyed in a blinding explosion.
Split into simpler sentences: She retreats and unsuccessfully attempts to abort the self-destruct, then returns to find the Alien gone. She narrowly escapes in the shuttle as the "Nostromo" is destroyed in a blinding explosion.