While working on a small nuclear reactor invented by a sympathetic giant scientist, the castaways are accidentally exposed to strange radiation that causes them to seemingly vanish or experience wild hallucinations. They then try to find a way to alleviate the symptoms. However, while Steve, Mark and Dan are away, an impatient Fitzhugh activates the device and it gets dangerously close to critical mass.
—Brian Washington <Sargebri@att.net>