The film opens with Sheriff Brody's youngest son getting eaten by a gigantic Great White shark in the waters off Amity Island. Soon afterwards, Ellen Brody says fuck this place and moves to The Bahamas to be with her eldest son Michael who is now a marine biologist. During all of this, Ellen has a strange sense of apprehension that the shark (who exactly is this particular shark by anyway?!) is going to follow her all the way to The Bahamas and eat her and her family. What the hell? On top of that, throughout the film she has some kind of psychic link to the shark. Wow! Somebody got paid to write this? Anyway, it ends up that she's correct and the shark soon shows up and starts terrorizing her family. He even knocks down an airplane!
Stretch that paper thin story into 89 minutes and you have the recipe for a truly bad movie. And how Michael Caine, just one year after his superb performance in HANNAH AND HER SISTERS got involved with this stinker would be a story better than the movie itself. He is quoted on Wikipedia as saying "I have never seen it [the film], but by all accounts it is terrible. However, I have seen the house that it built, and it is terrific!", so I guess that explains that.
Should you watch JAWS 4? That really depends on how bored you are and how fine-tuned your sense of humor is, because this is not a good movie at all...but it is hilarious. I say go for it! But don't say I didn't warn you.
According to what I've read about the JAWS: THE REVENGE novelization tie-in the reason the shark was so intent on killing members of the Brody clan is because it was under the control of a witch doctor who was pissed at the Brody's. Makes sense.
Part 1 - Jaws (1975)
Part 2 - Jaws 2 (1978)
Part 3 - Jaws 3 (1983)
That background looks fake as fook.