In a moment of boredom Shrek wishes that he were again a terrifying ogre and not a domesticated family man. His wish comes true, but, unfortunately, with a nasty catch and he must win Fiona's love all over again or face obliteration and leave the not very nice Rumpelstiltskin in charge of Far Far Away.
The franchise comes to an end and 'Shrek' lovers should see 'The Final Chapter'. It's still good, but given the wonderful three earlier films it was probably a good idea to call time on this series that will live long in the minds of a generation.