Shrek is getting tired of being a domesticated ogre and family man, wishing for those days when human villagers were terrified of him. So he signs a deal with Rumpelstiltskin. Shrek thinks he will have a day of freedom but what the little devious Rumpel did was prevent him from being born, so none of the events in SHREK 1-3 ever happened. Now, Shrek finds himself in an alternate timeline in which Rumpel rules the land of Far Far Away and has enslaved the ogres with his army of witches. Shrek re-friends Donkey and eventually meets Fiona, who is now a freedom fighter. Puss turns out to be her overweight pet cat. The only way Shrek can undo the contract he signed with Rumpel is to have Fiona fall in love with him again, yet when he kisses her nothing happens. She doesn't love him in this reality--so he must do something that will sway her feelings.
I found this fourth SHREK film better than the 3rd, but not nearly as entertaining as parts 1 and 2. The 3-D is effective and not overdone and Rumpelstiltskin makes for a great little villain.