With Nigel and Marianne off exploring bat caves, Eliza and Debbie are left at the ""eerie"" residence of colleague Dr. Renfield. Eliza becomes bent on spooking Debbie, but when her imagination gets the best of her the tables are slowly turned. By the time their parents return, the girls are convinced that the absent-minded Renfield is a vampire out to get them!

When Eliza sneaks out ahead of her parents in order to find a rare Sumatran rhino, she discovers that to expose his life would only lead extinction of the species. Now instead of taking the prized rhino to her parents, she must try to keep them from filming it. And the bad news is, Nigel's already on its trail!

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.

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.

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 goes to desperate measures to help animals survive during tough times along the Skeleton Coast. Her good-will intentions, however, will soon cost her family their entire supply of holiday cheer--and their Christmas dinner!

When Donnie kidnaps an aye-aye for a pet, Eliza must return the ""bad luck"" omen to his home before the villagers hunt him down.

When Eliza tries to swim with the humpback whales, Darwin accidentally knocks Debbie's boombox into the ocean, which creates a distrubing noise and causes the whales to stop their ritual singing. Eliza attempts to set things right, but ends up getting arrested for violating the Marine Mammel Protection Act.

The Thornberrys are visited by the Foundation's head son, Tom, who splits up the Nigel and Marianne team. An over-zealous Tom treats Eliza like a child until he lands the Commvee in a raging river. Eliza's quick thinking prevails and she saves her family and wins Tom's respect.

Location: The Florida Everglades, United StatesDebbie and Eliza explore the Everglades but drop Nigel's birthday present, a new watch, into the swamp. As an old woman chases them away, they return at night, only to have the watch eaten by an alligator.

Location: Lake Baikal, SiberiaWhen Eliza and Debbie slack off on their chores, they all suffer for it when they fail to prepare of an oncoming storm. Will the Thornberrys survive a flash flood, help some beavers build their dam and keep the Comvee from sinking?

Location: Kakadu National Park, Northern Territory, AustraliaThe Thornberrys meet an Australian family named the Gibsons when the Comvee runs out of gas. Eliza makes friends with the youngest member of the family named Bethany, who is in a wheelchair from cerebal palsy. The girls go land sailing and Bethany helps Eliza escape from a crocodile, but then get in an arguement when Bethany thinks Eliza is feeling sorry for her being disabled. Will the two new friends find a way to make up? Meanwhile, Nigel and Marianne play the Gibsons in a very competitive game of Tricky Trivia.

Location: Okavango Swamp, BotswanaIt's April Fools day, and The Thornberrys are trying to outdo each other by way of April Fool's jokes. At first it's a lot of fun, but when Tyler and Eliza encounter some quicksand and a lion, will they learn not to cry wolf? Meanwhile, Nigel coaches Debbie for her Physical Education courses.

Location: Borneo, IndonesiaThe Thornberrys are preparing for Donnie's ""birthday"" party in Borneo when one crisis after another happens. Grandma Sophie decides to visit the same day Nigel and Marianne must capture a wild orangutan on film or the foundation will cut their funding.