George and Ursula now have a son, George Junior, so Ursula's mother arrives to try and take them back to "civilization".

When the Mystery Inc. gang is invited to Spooky Island, a popular amusement park, they soon discover that the attractions aren't the only things that are spooky. Strange things are happening, and it's up to Scooby, Shaggy, Fred, Daphne, and Velma to uncover the truth behind the mysterious happenings.