Crystal Cove is being terrorized by a mysterious ghost truck that has been running people off the highways. Meanwhile, crystal doorknobs all over the city have been disappearing, The gang investigates, discovering that the truck is outfitted with unique tires. They follow the tire tracks to a secret hideout where all the crystal doorknobs are stashed. Meanwhile, while Mayor Jones is running against George Avacados for reelection, Barty and Nan Blake try to set Daphne up with wealthy heir Rung Ladderton. With Angel’s help, the gang finds out that Avacados purchased tires identical to those on the ghost truck, and that his father stole a priceless diamond long ago and hid it as a doorknob. Suspecting Avacados, the gang traps the ghost truck, only to discover its driver is Rung, who is not as wealthy as the Blakes believed and needs the diamond to restore his fortune.