The years have been unkind to Rarity. She has lost everything. Now, at rock bottom, Rarity searches out her estranged sister Sweetie Belle who is now residing in Manehatten. Unbeknownst to her, Sweetie Belle has totally moved on from her simple life in Ponyville and Rarity discovers that she may not have room in her heart for her big sister any longer...

I'll also add, although it ought to be obvious, this is a pony adaptation of A Streetcar Named Desire by the very talented Mr. Williams. But you can expect some glaring differences all the same.