Major Dennis, Danny, and Rex jeep through the mountains of Africa. They seek ancient cave paintings. But "stone age" critters - a giant boar, huge vultures, carnivorous fish - keep attacking for no known reason. Rex defends, but they're hounded everywhere. Spilled into a river, they emerge in the cave with the paintings. And see that a Rex figure was long ago worshiped for saving the local people. And the local animals still bear a grudge centuries later!
Now the Sheriff has a new craze, stamp collecting! He gets a mis-delivered letter and drives it to a relocated Spanish castle. No one answers, so Bobo scales inside - and spooks robbers! He hides in a suit of armor, spins on a weather vane, and bowls them over! The freed owner gives Bobo a stamp album, and now he has a new craze!
Rex and Danny visit Fort Williams near the Canadian border, an old Revolutionary War stronghold. But Danny notes the reenactors have their leggings on wrong. Rex smells evil and gets locked in a dungeon. He shimmies up the chimney as the crooks shell the town with an old cannon and demand ransom. Rex knocks them flying, bowls them over with cannon balls, even shoots an Indian arrow to capture all three!