Eliza accuses Darwin of losing his animal instincts, so, to prove her wrong, he wanders into the jungle where a stone age tribe feeds him well. But are they trying to help him or trying to fatten him up for a feast?
This episode takes place in Manaus near the Amazon River. The episode begins from the view of a dragonfly. It flies right over Eliza, who is standing in the middle of the jungle impatiently. Darwin comes out of the jungle panting and covered with sweat. It is apparent that he and Eliza have been on a very long hike. Eliza tells Darwin that they'll play rock-paper-scissors. If she wins they keep going on and if Darwin wins, they'll go back to camp. They play and Eliza wins the game with scissors cutting Darwin's paper. Darwin tries to argue that it's a flat rock, but Eliza pulls him along as they walk.
At the campsite, Debbie is looking through her Teenage Wasteland magazine while Donnie drums on the pots and pans on the counter. Debbie thinks that she needs a new look and tells Donnie to come over and look at the magazine. She asks if he can say hipster, but Donnie is unable to do that. Instead, he picks up the sunglasses and puts them over his eyes. Nigel and Marianne come back from doing a shoot with Nigel having to hold a hand over his eye. Marianne tells him that next time she says that she's going to do a close-up he's not supposed to run towards the camera. Nigel says he'll remember. Marianne tells him that she's going to get some ice. While Marianne gets it, Nigel waves a pen in front of his face and is very worried that he has lost total vision in his eye. Marianne tells Nigel to move his hand away. Nigel does, and realizes that he can see. Relieved, he starts playing a game by putting his hand in front of his eye and then removing it like a game of peek-a-boo. When he looks, he sees a native tribesperson hiding behind a tree. Nigel is amazed and yells for Marianne.
Back in the jungle, Darwin tries to swat at the dragonfly but he misses. Eliza shouts for him to come over to the nearby bushes. When they walk through, they see a small waterfall off of a rock ledge that they can jump off. Eliza tells Darwin to climb to the top. Darwin mocks Eliza and asks if they can sit down and relax for once. Darwin proceeds to stub his toe on something and he screams in pain. When he looks down, he sees it's some kind of crystal. He is actually very amazed at how much it shines. When Eliza climbs to the top, she jumps into the water below. She thinks it's a lot of fun and goes to jump again. Darwin tells Eliza to come see the rock he found, but Eliza isn't really concerned about it. Darwin thinks it's really cool, and he can actually see five different reflections of Eliza through it. When Eliza jumps into the water, she ends up splashing Darwin and he drops his rock on the ground.
Elsewhere, Marianne and Nigel try to track the native that Nigel saw in the jungle. Marianne is very anxious and tells Nigel to hurry. Nigel warns her that they don't know anything about the native's tribe so they need to proceed carefully. Nigel proceeds to fall over a rock and scrape his knee. Marianne looks behind to see what happens. Nigel shows her the rock that he tripped over and Marianne says that it's not just any rock. Nigel looks and notices that it's been sharpened to be some kind of tool. Marianne then shows him that they've come upon the village of the native. Nigel wonders if they are a civilization untouched by mankind. Marianne remembers a village in the Philippines that was discovered awhile ago that was untouched by civilization and thinks this might be another one. She wants to film them, but Nigel stops her. He tells her that their presence may put their way of life in danger. Marianne says that the Foundation might like to see something like this. Nigel says that the natives may not have seen equipment like the camera before and it might disrupt their way of life. Marianne agrees with Nigel.
Back at the waterfall, Darwin continues to look for his rock that he dropped while Eliza continues to jump off the waterfall and splash Darwin. Eliza tells Darwin to hop in the water with her. Darwin tells her that he doesn't want to and adds that he's too busy looking for his rock. Eliza asks if he's sure he even had a rock. Darwin insists he did, but Eliza made him drop it. Eliza thinks that Darwin looking for a rock versus diving into the water isn't much of an adventure at all. Darwin tells her that when he lived in the Congo every day was an adventure for him.
Eliza tells Darwin not to be like that and tells him that he won't even climb ten feet without complaining first about it. She adds he's less like an animal than any that she's met. Darwin is very insulted. Eliza tells him that he's been around humans so long that she thinks that he's lost his animal instincts. Darwin says that he's wild and untamed. Eliza says that he's being a crybaby and doesn't think that he would last a day in the jungle. Darwin starts to walk away and Eliza thinks he's going back to camp. Darwin tells her that he's going into the jungle. Eliza asks what he wants there. He says he's going to do chimpanzee things. Eliza tries to talk Darwin out of it, but he doesn't listen to her. Darwin stomps off. Eliza just lays in the water frustrated.
Back at the convoy, Eliza arrives to find Debbie ruffling through her clothes. Eliza asks Debbie where Donnie is. Debbie says that Donnie is under the stack of clothes, and adds that she can't believe that none of her clothes are black. Eliza finds Donnie under the stack of clothes and asks if he wants to go jump off of the waterfall with her. Donnie gets very excited when Eliza mentions the adventure. Eliza tells Debbie that she's taking Donnie into the jungle. Debbie says she doesn't care, and after putting on a black cap, she starts acting like she doesn't care.
In the jungle, Darwin walks by the river on all fours like he used to when he was in the Congo. He realizes that he is thirsty but when he cups water into his hands, it doesn't stay. He grabs a large leaf from a tree and puts it in the water. He is able to get water using that method and he is able to drink. When he dunks the leaf in a second time, a snapping turtle bites Darwin's finger and Darwin screams in pain. He starts to suck his finger and keeps walking.
At the waterfall, Donnie and Eliza are having fun jumping into the water. Donnie climbs even higher on the rock and Eliza decides to follow him. Eliza says to wait until the count of three to jump but Donnie jumps very early. Eliza follows and they both agree that jumping from the higher point was a lot of fun.
At camp, Debbie is continuing her new fashion when Nigel and Marianne come back. Nigel and Marianne come back to the camp and Nigel asks Debbie if she can guess what they saw. Debbie thinks they saw loneliness. Nigel says no and tells her that they found a Stone Age tribe. Marianne adds that Nigel won't allow any filming. Nigel says that he thought of something. He says that if they disrobe before they go in, they won't be disrupting anything. As Nigel starts taking off his clothes, Marianne tells him that they could just film from the bushes they were at and assures him that nobody will spot them. Nigel says they can do that.
Back at the waterfall, Eliza is starting to get tired from all of the jumping she's done. She tells Donnie that it's time for them to head back to camp. Donnie yells that he wants to jump more. Eliza says they've been jumping all day and asks if Donnie is hungry. Donnie starts munching on a plant that was on the ground. Eliza tells Donnie to stop eating that and that they need to go home. Eliza starts pulling on the plant that Donnie has and after a short struggle, the plant breaks and the two fall on the ground. Donnie starts laughing, but Eliza retorts that it isn't funny because she fell on something sharp. She realizes that it's Darwin's rock and says that it really is a cool rock because it makes rainbows.
Back at camp, Marianne puts the dishes on the table for dinner. She doesn't realize Debbie's new personality and asks if everything's alright. Debbie says that she is unable to answer that question. Marianne asks if Eliza told her when she'd be back. Debbie asks why that matters. At that moment, Eliza and Donnie return from their day of fun. Eliza comes back and asks Marianne if she's seen Darwin. Marianne says no and thought that Darwin was with her. Eliza really thought he would be back at the convoy by now. Nigel wonders if Darwin is lost. Marianne assures everyone that Darwin will probably be home soon when he smells the dinner that she made.
In the jungle, Darwin hears a lot of rumbling and growling in the jungle. He is very scared, but realizes that it's his stomach rumbling. Darwin goes to a log and puts a stick inside of it. He is able to get several ants on the stick and he eats them. Unfortunately, they don't satisfy his taste buds anymore and he spits them out onto the ground. Darwin is sad that he has to stay hungry.
Back at camp, Eliza continues to shout for Darwin. Eliza is unable to find Darwin, and Marianne brings a dinner of hamburgers outside. The family gathers around the table to eat without Darwin. Eliza doesn't take any food to eat and says that she's not hungry. Debbie is at first disappointed by the dinner, but realizes that they are hamburgers. She gets really excited and starts eating them quickly. Marianne informs her that they are actually capybara burgers. Debbie asks what a capybara burger is. Nigel points over to the convoy and says that one is over there. It's a very large creature, and Nigel informs Debbie that a capybara is a very large rat. Debbie is very disgusted.
Without a word, she pushes her plate away and heads back inside the convoy. Marianne notes that rat probably wasn't the best word to use. Nigel agrees with her. Donnie thinks that the dinner is good and finishes the rest of Debbie's capybara burger. Eliza asks Nigel if Darwin is coming back. Nigel doesn't think that Darwin would like the Amazon as much, and notes that it's hard to resist the capybara burgers. Hearing capybara again, Debbie starts to get sick and runs to the bathroom. Marianne assures Eliza that Darwin will be fine and will probably be back by morning. Nigel thinks that Darwin might be eaten. Marianne is very upset that Nigel said that. Nigel says he was only joking and assures Eliza that Darwin is fine. Marianne says that chimpanzees are good at surviving in the wilderness. Nigel assures Eliza that Darwin is probably high in a tree building a nest to sleep in. Eliza asks if he really thinks so. Nigel at first wants to express his doubt, but Marianne's glare makes him assure Eliza that Darwin is fine.
In the jungle, Darwin is making a nest in the tree. He is able to make it between two trees and he lies down in the nest. Before he is able to fall asleep, the nest starts snapping. It falls apart and Darwin falls down to the ground. He starts to hear growling again and this time he knows that it isn't his stomach. Suddenly, lightning lights up the skies and it starts to rain on him. Darwin goes inside a tree to take cover, but he looks around and notices that there are two jaguars inside. He gets scared and starts running through the jungle. He thinks that there are many eyes staring at him and he is very frightened. Finally, he comes upon a village; the same village that Nigel and Marianne came across. He sees a lit hut and smells a nice meal cooking. He sees turkey cooking over the fire. Darwin sneaks in and eats the turkey. Now that he's full and by a warm fire he is finally able to go to sleep.
Back at camp, Eliza runs outside and starts shouting for Darwin. She thinks that something happened to him. Meanwhile, Darwin is awoken by one of the natives that live at the camp. The native has a pear in his hand and offers it to Darwin. Back at camp, Eliza continues to shout for Darwin. Suddenly, Donnie appears in front of her and tries to get her attention. Eliza tells him that she is looking for Darwin. Donnie starts pulling Eliza and starts acting like Darwin. Eliza continues to tell him to stop. Donnie points down and Eliza looks. There are footprints on the ground that looks like Darwin's. Eliza realizes that the footprints lead to the village.
In the hut, the natives continue to feed Darwin fruit. Darwin is very happy that he is well-fed. Eliza looks inside and sees what is going on. Eliza thinks that Darwin is happy with the tribe and says that he probably doesn't want to come back to camp. Eliza is still holding onto Darwin's rock and she throws it away. It ends up flying through the hut's window and hits Darwin in the head. He realizes that Eliza threw it and goes to run out of the hut. One of the natives grabs him and tries to feed him again. Darwin breaks free and tries to run but the native is able to catch him again. This time, Darwin is thrown in a cage and Darwin screams for help.
Back at camp, Eliza is still upset about everything. Nigel and Marianne tell Debbie and Eliza to come see the village with them. Debbie tells them that she is going to stay at camp and dye her hair and all of her clothes black. Marianne is very confused about Debbie's intentions and then asks Eliza if she is going. Eliza says she's not. Marianne knows that she's upset about Darwin, but she tells her that it will be fun seeing the Stone Age Village. The girls both doubt it will be fun. Marianne continues to try and get them to go, but the girls reject every request. Marianne starts to get upset and says that they should do. Eliza starts to have an attitude and asks if she's going to make them go.
Later that day, Eliza and Debbie were forced to go and they stand back while Marianne and Nigel film the natives starting to get everything ready for a meal. Debbie thinks this is dumb. Marianne asks what Debbie wants. Debbie tells her that she wants new clothes, drums, and she wants to be allowed to drink coffee. Nigel continues to observe the natives and he sees them bringing out an animal in a cage for their meal. Nigel realizes it's a chimpanzee and Eliza realizes that they might eat Darwin. Eliza starts running down to the village. Nigel and Marianne try to stop her, but they both end up tripping and falling down. Debbie tells Donnie to follow her. Nigel starts to get up, insisting that he's fine. But Donnie ends up flying into Nigel and it stuns him again. Eliza is able to make it down to the village, and before the natives can put Darwin in the pot, Eliza swings down on a vine and is able to grab Darwin. Darwin thanks Eliza for saving him and Eliza apologizes to him for saying the things she said. Darwin apologizes for missing the branch on the tree and they swing back towards the pot. Debbie pushes one of the natives out of the way so he doesn't get hit. Eliza tries to grab the branch, but also misses. She asks Darwin if he's gained weight and Darwin sheepishly says no. They end up crashing into Debbie and the native and spilling the pot all over the ground.
Nigel starts apologizing to the chief for everything that they've done. He thinks that the chief doesn't understand him and starts jumping around like a monkey and saying he's sorry for taking their meal. The chief reveals he does speak English and says that it's alright. Nigel is amazed and the chief says that he could let Nigel borrow his English tapes because he thinks he could use the practice. Nigel can't believe it, and the natives reveal they are updated to all technologies. They reveal that they have phone, and he uses one to call one of his friends to bring some steaks down to the village. They also have video games and computers. Debbie tells them that one of the natives, Tiko, has his very own website. Marianne can't believe they have all these things and the chief tells them that everyone does and they should get with the 21st century. Marianne apologizes and admits that she thought they were more primitive. The chief says that they still live like that, and says that a laptop and a few phones won't change that. Debbie shows Nigel and Marianne a dress that Tiko is giving to her. Marianne thought that Debbie was only wearing black from now on, but Debbie says no.
Eliza and Darwin are still playing with the rock that Darwin found. Eliza says that they should play a game of Rock-Paper-Scissors. She says that if she wins, they're going on an adventure and if he wins they'll go back to camp. Darwin accepts the challenge. When they reveal their choices, Darwin uses his rock as a rock and Eliza uses paper. Eliza wins and tells Darwin to come with her. Darwin tries to argue that it's more like scissors. The episode ends with Darwin running after Eliza.
Nigel:Probaly not. Morning? Ha! Something would have eaten him by then.
Eliza: (gasps) Eaten?!!?
Marianne:Nigel!(Stabbing him with a fork)
Nigel: Oh Blast! Did I say eaten? I meant fine. He'll be fine.