Raoul Duke and his attorney Dr. Gonzo drive a red convertible across the Mojave desert to Las Vegas with a suitcase full of drugs to cover a motorcycle race. As their consumption of drugs increases at an alarming rate, the stoned duo trash their hotel room and fear legal repercussions. Duke begins to drive back to L.A., but after an odd run-in with a cop, he returns to Sin City and continues his wild drug binge.

The Mystery Inc. gang have gone their separate ways and have been apart for two years, until they each receive an invitation to Spooky Island. Not knowing that the others have also been invited, they show up and discover an amusement park that affects young visitors in very strange ways.

The plane carrying wealthy Charles Morse crashes down in the Alaskan wilderness. Together with the two other passengers, photographer Robert and assistant Stephen, Charles devises a plan to help them reach civilization. However, his biggest obstacle might not be the elements, or even the Kodiak bear stalking them — it could be Robert, whom Charles suspects is having an affair with his wife and would not mind seeing him dead.