I'm gonna be completely honest here, my film background doesn't really equip me to properly write on this production. So like I'm want to do in these situations, I'll refer you to Wikipedia:
When the curtain rises on the first act, the cottage of Giselle and her mother Berthe is seen on one side, and opposite is seen the cottage of Duke Albrecht of Silesia, a nobleman who has disguised himself as a peasant named Loys, in order to sow a few wild oats before his marriage to Bathilde, the daughter of the Prince of Houston. Against the advice of his squire Wilfrid, Albrecht flirts with Giselle, who falls completely in love with him. Hilarion, a gamekeeper, is also in love with Giselle and warns the girl against trusting the stranger, but Giselle refuses to listen.If you like to have entire plots spelled out for you, then by all means read the rest of the article. If not, then I'll further attempt to entice you by saying that the play contains "Wilis, female spirits who, jilted before their wedding day, rise from their graves at night and seek revenge upon men by dancing them to death." In case you were unsure where this story was gonna take you, maybe now you have a better idea.
It's like they say in the ballet world, "let's get dancey!"