Saul, a fennec fox who thinks more like a lone wolf gets paired up with the neighborhood Tortoise and his favorite prank victim, Ziva. Saul refuses to accept their fate, and makes several increasingly dangerous attempts to break the knot before it becomes permanent. In doing so, they attract the attention of Eagle and Falcon, the desert’s top T.T.A agents, whose entire goal is to keep pairs together. Tension builds between Saul and Ziva, and they wreck the desert’s primary transportation system - Zip Station - in their final attempt to separate. They make amends at their surprise Pair Up Party, and Ziva agrees to help Saul cross the world in search of someone who can help them get untied, if that will make him happy.

Goliath has been alone her whole life and wants to find the Key Maker to get a pair. She hears about Saul and Ziva’s plan and practically forces herself onto their team, promising that she has some information about the road to separation. All she can remember for now is that she heard that there’s a person who got untied, who lives on the “Third Claw,” whatever that means. The trio reaches their first obstacle - an endless canyon, nearly a mile deep, running as far as you can see in both directions. Built into the cliff walls are the colorful bird houses of Avery City. The only way across is to fly in one of AC’s tandem flying machines, which were built to accommodate birds who can’t fly because of the way they’re tied (or birds who can’t fly at all!). The machines only require one thing to operate them - trust. Birds don’t struggle with this at all because they’re the masters of relationships. That’s why the expression is “love BIRDS”. Saul and Ziva barely make it off the Trust Fall, Goliath can’t fly solo, even with 8 arms, and the birds are too afraid to help her. The birds put Saul and Ziva through a series of ridiculous and challenging trust and flight training sessions, and ultimately get them to realize that they genuinely want the best for each other. They manage to just barely make it across the canyon. Goliath learns to trust in herself, but only makes it with a bit of help from a couple of finches who manage to conquer their fear of spiders and trust her. As Saul and Ziva soar way higher than expected, they realize that the desert looks like a paw print when seen from above. The Third Claw is a place on the desert’s “paw,” and it’s not so far away.

The group reaches the Third Claw and - supposedly - the only person who has ever made it to the Key Maker and back: a grumpy old PLATYPUS, who lives alone on a small island. He tells them what they’ll need for their journey, including the strange things that the Key Maker demands as payment, many of which can only be found on his island and seem to be things that the Platypus just wanted for himself but were out of his reach. Ziva - the least judgemental person in the group - can’t shake the feeling that the Platypus is lying. Saul refuses to listen to her, blinded by his obsession with getting untied. While the group gathers their supplies, Platypus rambles nonsensically about his adventure and the person he allegedly got untied from. His reasons for wanting to get untied are petty, and everyone thinks about the golden question: If we really could choose to live alone, would we? Ziva discovers that Platypus is a fraud - tied with a tiny rope to a flea in his armpit. Saul loses his temper and is scary enough to get the Platypus talking. The Platypus admits that he was lying, but he swears he actually attempted the journey and that the map is real. The T.T.A stole it from him when he was just a day’s journey away from the end and covered up the evidence by putting it in a Museum, labeled as something else.

The trio heads into the Museum of Myths and History. That day, an elite prep school is on a field trip. This school is famous for pairing kids up (i.e. handcuffing them) when they’re young so that their bond automatically forms with the “right” person when the time comes. Saul and Ziva are fascinated by the kids, who seem totally cool and nonchalant about their circumstances. Through their discussions, Saul and Ziva accidentally start a small uprising, and all of the students start asking to switch who they’re tied to, or even leave it up to fate. Meanwhile, Goliath can’t get into the museum because she’s not a pair, and the museum scans the magical rope for entry. She sneaks in through the roof and discovers some shady Night Watch Possums, who are up to no good. Saul and Ziva realize that this uprising could bring them unwanted attention and attract the T.T.A again, so they drop their search for the map in order to shut it down. The original pair of kids they met runs all around the museum, cutting deals with everyone in their school to create an entirely new arrangement of pairs. While chasing these revolting pre-teens, Saul and Ziva wind up in a less popular branch of the museum that houses the map. Goliath shows up at the same time. The map is labeled as something else, but there’s no mistaking it - the picture of the person on the map is alone. He’s not tied to anyone. This MUST be the map they’re looking for. The guards find Goliath and kick the group out, along with an entire class of crying, screaming, revolting pre-teens.

Realizing that Platypus wasn’t lying about the map, the group assumes he was telling the truth about everything else too. So they have to get a laundry list of supplies that he claimed are “essential” for the journey, starting with Rattlesnake Venom that they supposedly need as payment for the Key Maker. It’s no secret where to find the venom, but the snakes know how valuable it is, and it’s unbelievably expensive. The group takes a tour of the venom factory, which is like a sinister version of Willy Wonka’s Chocolate Factory. Snakes everywhere. Mice instead of Oompa Loompas. And every day, the factory hosts competitions to win a vial of venom. Saul almost wins at an agility challenge, dodging strikes from the guide. He really is quick, and she cheats to make sure he loses. The group fails at every competition and gets distracted by side rooms and whimsical traps that hold the promise of reaping a few drops of the dangerous liquid. In the end, Ziva goes toe-to-toe with a snake in a venom-drinking contest and loses. Through their bond, Saul feels her pain and realizes how much she must care about him to endure that much venom just to get untied. Saul begins insulting the guide, until she strikes, then he whips out two vials and catches her fangs in them. He really was faster after all.

Eagle and Falcon close in on the trio in a seemingly empty desert. There’s nowhere to hide ... Until a meerkat beckons them into his tunnel. Suddenly, the group realizes that there’s an entire CITY under the desert floor with tunnels of all sizes for creatures of all sizes. Ziva lets it slip that they’re being hunted because of their mission to get untied, which leads to pandemonium in the tunnels! The smaller the creature, the faster they work. In one day, the entire city goes through every phase of the Untied Revolution. Saul, Ziva, and Goliath do their best to quell the uprising and keep it contained in Subterraneania because if word got out, they’d be wanted by a lot more than just the T.T.A. Amidst the chaos, the group notices the Nightwatch Possums from the museum poking around the tunnels, which is odd because possums don’t live underground. They do a little recon and learn that the possums are planning on tunneling into the museum and stealing the map. A chase ensues as the revolution turns into an all-out war (mostly between between mice and hamsters). Goliath manages to snatch the possum’s blueprints of the museum, and the entire city comes crashing down. Saul realizes that if everyone tries to get untied, there would be chaos, begging the question: can something be moral if only a few people can take advantage of it?

The trio plans to rob the museum and steal the map before the possums do, in order to protect it (and also use it). They barely start planning, when Eagle and Falcon trap Saul and Ziva and drive them to a secret facility. The pair tries to warn everyone about the possums, but no one believes them. Goliath escapes to a nearby town full of small animals who are all afraid of her. She tries to convince them that she isn’t a killer, but they don’t believe her or give her refuge, so she scurries away into a cave. Saul and Ziva are suspended over a pool of sharks in a T.T.A facility. One of them is a Greenland Shark - the animal with the longest lifespan in the world - who claims to be 450 years old. His mind is a little cloudy, but between his ramblings, they realize that the T.T.A dates back to ancient times and there was a huge cover up / conspiracy that no one knows about anymore. In their “all is lost moment,” Saul and Ziva connect in a way that they haven’t before. Saul actually apologizes, and their rope glows a little brighter. Meanwhile, Goliath watches from afar as the bird police bully the small town and take advantage of its citizens. Alone, scared, and upset at the injustice, Goliath removes her fang caps and releases her inner animal. Fired up from the fight, she goes after the T.T.A facility. She busts in like a secret agent and rescues Saul and Ziva. After years of trying to make everyone like her and trying to be something she’s not, this is a huge moment for Goliath. It’s already night, and the possums have definitely already begun their heist. There’s no time to spare!

The trio arrives at the museum, tardy to the party. The possums have already tunneled in, and they’re looting the most valuable items. They haven’t gotten to the map yet, but Ziva refuses to take the map until they’ve put a stop to the possums and returned all of the other items. Saul has no choice but to agree. Eagle and Falcon arrive at the scene, but they’re held back by the B.H.T (The Bureau for Handling Things - this world’s equivalent of the CIA). With the Subterreania uprising, Saul and Ziva’s journey has become a national emergency. Saul and Ziva manage to work together to steal back most of the items. The possums catch on and a battle ensues. One of the possum’s acquaintances - a wombat - is not tied to anyone. He and Goliath face off. Goliath wins, but the wombat tells her that more and more people are being left without a pair these days. It’s not 1-in-a-billion anymore. Ultimately, the possums and their crew are captured by the B.H.T, while Saul, Ziva, and Goliath steal the map and escape through the possum’s tunnel. They make it to safety and open the map. It has directions to the KEY MAKER - a legendary creature who can untie people. They now have a destination for their journey, but they won’t succeed that easily… Half of the map has been torn off, with a note from the previous owner: “If I can’t make it, no one can.” With that, they walk out of the desert, for the first time in their lives.