The Thornberrys are in Africa near Mt. Kilimanjaro to film lions. Debbie pleads with her mom to let her drive the comvee while she films and Marianne reluctantly consents. Debbie loses control of the comvee and it falls down a muddy river bank. Before they can get it out a storm erupts and the comvee is washed away. That night while camping near the river Debbie goes off on foot in pursuit of the comvee while Eliza goes off in pursuit of her and Darwin and Donnie go off in pursuit of her. Soon all become prey to a lion and two lionesses. Eliza will have to outwit them...
The Thornberrys are in Africa along the banks of the Congo River. They have three days to catch a freighter at Matadi but if they miss it they will be stuck in Matadi for eight weeks. On the barge on the way to Matadi Eliza discovers that Kip and Biederman are also on board and they have a captured hippo with them which they plan to sell to a zoo. While helping the hippo escape Eliza, Darwin and Donnie fall overboard.
The Thornberrys are in Brazil near the Amazon River when Eliza starts to feel as if nobody is paying any attention to her...Debbie is consumed with herself and her parents are fussing over Donnie. She and Darwin head into the jungle and take a ride down river. Whne they disembark they find a jaguar trapped in a pit. She helps it to escape and the jaguar family thanks her. Eliza is so delighted to be paid attention to that she creates a fairy tale story and convinces the jaguars that she is their princess.
A huge forest eating machine is destroying the Amazon forest. Nigel and Marianne set out to find government help in stopping it while Eliza teams up with the animals to fight it. Debbie's attempt to listen to a radio show are being thwarted by a radio that continually breaks down.
The Thornberrys are camping on the banks of the Amazon river so Nigel can perfect his insect repellent formula. Eliza becomes fascinated with a fresh water dolphin that she sees out in the river. Debbie is bored as usual when a teenage girl from the village wanders into camp. She and Debbie begin hanging together while Eliza worries that she could be a legend come true...a dolphin that takes the form of a young girl. Could Jao be a dolphin in human form?
The Thornberrys are in Uganda's Impenetrable Forest to film the rare bird The Great Crested grebe. While Marianne and Nigel go off to film the girl's argue over the use of the tape player. In the ensuing argument Debbie releases the commvee's brake and it takes off downhill. It finally comes to rest on a muddy river bank where it is firmly stuck. The girls will have to work together to free it.
The Thornberrys are driving in the Andes Mountains in Peru on the way to visit Dr. Spinoza the world's foremost authority on vampire bats. This is a special trip for Marianne who was a student of Dr. Spinoza's twenty years ago. On the way Eliza starts reading about bats and her movie memories about vampires starts spooking her a bit. Dr. Spinoza lives in a remote, big castle and he is not at all like Marianne remembers. Everything about him gets Eliza's imagination going and Debbie sees it as a chance to have some fun at her sister's expense.
The Thornberrys are on the Gallapagos Isalnds to film the return of the sea turtles. While off exploring with Darwin and Donnie, Eliza gives a finch an unfair advantage in getting food and in so doing disrupts the delicate food chain of the island.
Eliza and her father set off on foot to scale the Andes. Nigel assures Marianne he will be very careful and keep close tabs on Eliza. Marianne is upset because her mother sent a care package. She thinks her mother doesn't think she's a good mother. While scaling the mountain Eliza can't stand her father's over protectiveness and wanders off on her own...right when a blizzard strikes.
The Thornberrys are in the jungle of Sumatra where Nigel is in pursuit of his lifelong dream...to see a Sumatran Rhino in the wild. Eliza and Darwin set out to help him find it while Debbie and Donnie find some surfing teenagers.