Danny and Rex do a bicycle high-wire act at a visiting circus as amateur talent. But when the acrobats are injured, pretty Marle asks their help to keep the family's performance contract. Rex stops elephants and rescues the two when stranded on the high wire - but it's Danny who gets the hug from the pretty aerialist!; Shipped on a plane, Rex should be "baggage", but a stewardess lets him ride in the cabin. Rex smells evil as two crooks enter the cockpit and sky-jack the plane. Lost in fog, it crashes onto a mountain top. Rex slips out and treks through fog to a town, then leads the law back, even gets the jump on the crooks. Back home, he receives a citation and "promotion" to Airline Detective!; The Goliath Gang steals safes and breaks them open. The Sheriff asks Bobo for help, and Bobo opts for brawn over brains. He builds a huge crazy jungle gym in the back yard to work out. From atop, he spots the gang but gets brushed off. Finally he topples a painter's scaffold on the villains. And opts for brains over brawn from now on.