When the Thornberrys visit Nigel's friend Jomo, they search for an elephant named Rebecca that Nigel saved 20 years earlier. As the family attends to an elephant stuck in a mudhole, Eliza bonds with Rebecca, only to learn that she is old and ready to die.

Debbie discovers Eliza ""talking"" to dingoes and threatens to tell her parents. Eliza, concerned about the possibility of being shipped back to the United States as a science experiment, seeks help from nearby Aborigines. Together they confuse Debbie into thinking it was just a bad dream.

Eliza tells Darwin the tale of how she became able to speak to animals, and how she retained her ability to speak to humans as well.

With the commvee broken down in the desert and no water left to survive, the Thornberrys go through desperate measures to maintain their sanity. However, on the verge of dehydration, Eliza convinces her family to perform the rain ritual pictured in a nearby monolith. Everyone cheers as the rains pour down among them.

Eliza gets in over her head when she assumes responsibilities she can't handle. She is soon forced to don scuba gear and rescue a fumbling Nigel and a tumbling commvee under the dangerous waters of Australia.

Eliza succumbs to peer pressure from a ""teenage"" elephant, which gets in the way of her closeness with Marianne on an overnight trip.

Eliza convinces a mother kangaroo that she can handle the responsibilities of baby-sitting. She quickly learns that this mischievous joey is more than meets the eye. After a close encounter with Tasmanian devils, Eliza is all too happy to relieve her duties and go back to being a kid herself.

When the Thornberrys leave Australia for India, Eliza can't bear to leave her wombat friend, Emily. Even though she is told not to, she brings her along. Now Eliza is constantly forced to re-create Emily's habitat in order to ensure her survival.

To study and protect the snow leopards from extinction and a construction site that is threatening their survival, Nigel's mentor (thought to be lost for many years) has left civilization to be a yeti. Eliza discovers his identity, helps him fend off the construction workers, and reunites him with her father.

The Thornberrys get stranded on an uncharted island, basking at first in all the beauty and the splendor, but discover soon enough that being marooned isn't all it's cracked up to be.

When a seemingly abandoned panda bear imprints on Debbie, Eliza doubts Debbie's ""parenting"" ability--until a monsoon convinces Eliza that Debbie can handle more than she lets on.

Eliza frees a hyena from captivity, but having never lived in the wild, it doesn't know how to survive. Eliza attempts to teach it, but it seems hopeless--until a wild boar threatens them and the hyena's natural instincts take over.

Darwin brings Eliza to his chimpanzee compound, and Eliza, who isn't used to the structure of the chimpanzee way of life, puts Darwin in an uncomfortable situation. After a fire starts, Eliza realizes the hierarchy is necessary for jungle survival. In the end, she apologizes for her lack of understanding and the chimp leader lets Darwin off the hook.

The Thornberrys discover that koalas are missing from their native groves. Eliza decides to unravel the mystery only to discover Kip and Biederman masterminding the evil plot. It is now up to her to stop the culprits from wiping out an entire species!

The Thornberrys meet the Fensterkopfs who make false documentaries. The Fensterkopfs' kid lies to Eliza and gets them all stuck on a cliff. After the families barely escape an avalanche, the value of truth is learned by all.

When the Thornberrys are in Finland for the annual reindeer races, Eliza feels left out. She single-handedly uncovers a plot to sabotage the races, and along with an equally excluded reindeer who didn't make the final cut, helps save the day by playing fair.

When a friendly polar bear is wrongly accused of vicious behavior, Eliza goes to great lengths to keep him from being harmed and learns the value of sticking by a friend in times of trouble.

Challenging an ancient Maasai legend, Eliza marches into a ""haunted"" forest to prove her bravery. Now, with night falling, Eliza must place her trust in the mysterious legends of the Maasai in order to find her way safely through the dark forest.

The Thornberrys are invited on a cattle drive by Marianne's old high school friend whose son, Miguel, is not as adept at riding and roping as he claimed. In the end, Eliza helps him build confidence.

Eliza and Debbie are fighting so much, Debbie decides to apply to boarding school and Eliza encourages her. But meeting up with a lone wolf teaches Eliza that families, like packs, belong together.

When Eliza gets a hunch that foul play has led to Darwin's disappearance, she sets out to rescue her long lost companion. To her dismay, she finds Darwin has become one of the most popular acts at an Indian palace where a young prince lives. It's up to her to prove to Darwin that friendship runs deeper than the glamour and glitz of showbiz.

When the Commvee is surrounded by angry seals, Eliza tries her own methods to get them to move. But she learns from her Inuit friend Jim that traditional ways have their value.

When Kip and Biederman cause an oil spill, Eliza must save her sea otter friends.

Eliza reunites with a Siberian Tiger, and is stunned when the tiger turns on her. Eliza's visiting Grandma Sophie helps her overcome her fears just as she is overcoming her own.

Eliza and a Chinese girl, Arioka, secretly switch places so Eliza can ride across the desert on camels and Arioka can ride in the Commvee. But Arioka's parents change their plans and Eliza must figure out a way to get them back to the Thornberrys.