Jimmy Gibson and his older brother Bill are flying to America by plane with Mitch the monkey when their plane crashes. The Air Sea Rescue team can find no trace of their life raft through the dense fog, but at Black Rock Laboratory, the newly-completed Supercar is ready to be put to the test and Mike Mercury flies out to rescue the trio.

Masterspy and Zarin use a phony distress call to lure Supercar to them, and after they have Mike captured and drugged, who will be able to stop them from making off with the super vehicle?

With Dr. Beaker's unwitting help, Masterspy locates and steals the legendary lost talisman of Sargon, which supposedly has magical powers that will allow him to take over an oil sheik's riches.

An Air Force test to explode a new rocket fuel in the upper atmosphere goes awry, and only Supercar has a chance of getting close enough to detonate it before it falls back to earth.

When Mitch the monkey falls ill with sleeping sickness, Mike and Dr. Beaker head for the Amazon jungle to retrieve a special plant that can cure him, but they are captured by a tribe of headhunters.