Jack Watson is celebrating his 81st birthday. He is a charismatic, successful patriarch who still enjoys life. He makes a wish that he could be 18 again. Later he is living it up with his grandson, when the car they are driving in crashes, and their souls are switched. After the crash, 18 year old David Watson's body, with 81 year old Jack's mind (George Burns voice), is fine, but Jack's body is in a coma, presumably with David's mind trapped there. Walking in David's shoes, Jack discovers that...

Three odd-ball scientists get kicked out of their cushy positions at a university in New York City where they studied the occult. They decide to set up shop in an old firehouse and become Ghostbusters, trapping pesky ghosts, spirits, haunts, and poltergeists for money. They wise-crack their way through the city, and stumble upon a gateway to another dimension, one which will release untold evil upon the city. The Ghostbusters are called on to save the Big Apple.