It all begins at the beach where the PAW Patrol pups are having fun. Marshall wonders when Ryder will return. Rocky and Zuma pondered the same thing until then Ryder rallied the pups to the Lookout for their surprise. The pups are happy to see Ryder until he called a new PAW Patrol member, Rex. The Paw Patrol are happy to meet him and they welcomed him into Adventure Bay, Zuma commented on how his wheelchair is cool. Rex tells them that it helps him move around. Rex' name drops the six PAW Patrol pups and mixes up Rubble and Rocky. Skye is shocked to see that Rex is the only pup from Dino Land and then Ryder tells Robo-Dog that they are ready to go. Marshall asks if they were taking the PAW Patroller, but Ryder decides to take the Dino Patroller as it was the only way to get to Rex' home.
Along the way, Mayor Humdinger and the Kitten Catastrophe Crew are on the way when they notice the new Paw Patrol vehicle, with evil intentions they trail the PAW Patrol behind. They head via Jake's Mountain to a big cave ornamented by prehistoric creatures. They pass through a cave and then emerge behind a waterfall. The pups are in awe of the place and feel a rumble. They go outside and are amazed of the number and variations of the dinosaurs, and Rex welcomes them to the Dino Wilds. Rex tells them about Velociraptors, Triceratops, and Pterodactyls. Rocky then comments that Rex knows a lot of dinosaurs. Rex guides them to his place, a Dino Vet Center. Marshall is shocked, supposedly seeing a talking dinosaur, but it turns out that the "talking dino" are really people, a girl named Taylor Turbot and her mother, Dr. Turbot. Taylor, recognizing the PAW Patrol through their uncle, Cap'n Turbot, greets the pups. After the introductions, they head to the Dino Patroller.
Meanwhile, Mayor Humdinger, emerging from the waterfall, complains that there are no bare necessities to survive and notices a dinosaur causing the kitties to run away. Mayor Humdinger schemes to take dinosaurs to the outside world to use as an attraction for people. He chases the triceratops and along the way he notices an egg. He decides to steal and leave. Meanwhile the Brachiosaurus, seeing her eggs are missing, becomes distressed and starts destroying the Dino Vet center. Dr. Turbot notices its distress and calls the PAW Patrol.
At the Dino Patroller, Ryder receives the call and Ryder summons the pups to the Dino Tower. The pups are in awe gearing up and seeing the view of the tower and the dinos below. Ryder tells them about the new gear. He summons Rocky for repairs, while Chase and Rex are ordered to herd the dinosaurs and then the team begins to head to the rescue.
Rocky then begins to repair the center, while Rex asks the mama why she is distressed. She roars and Rex translates that someone had stolen the eggs and wonders who would do something so sinister. Ryder then instructs Rex, Rocky and Chase to scour the jungle and Skye at the air to look for the person who steal the eggs. Mayor Humdinger steals the triceratops and t-rex' eggs. The PAW Patrol searched until the t-rex chased them and Rex managed to stop them. Along the way, they found tracks. Ryder thinks that someone else had found a way to the Dino Wilds.
Mayor Humdinger search the tunnel home and along the way the eggs hatched. Timingly, the PAW Patrol cornered him. Mayor Humdinger tried to denied it but the egg hatched. Skye commented they are cute and Mayor Humdinger kidnaps the Baby Brachiosaurus. They felt a rumbled and notice mama Brachiosaurus heads after mayor humdinger. And Mayor Humdinger falls back to the bottom and Ryder called reinforcements to save the dinos from the rockslide. Marshall and Skye then saved the baby Brachiosaurus.
While at the bottom the Triceratops destroyed Mayor Humdinger's kitten carrier and surrendered the baby to it. Mayor Humdinger then gets the T-Rex and makes a break for it. Chase and Rex are gone after the baby. The Baby T-rex trips Mayor Humdinger and flings himself to safety. Chase bounced the baby back and Rex caught it using his Dino Claw. The T-Rex are happy and they stomped Mayor Humdinger's hat and Mayor Humdinger left the dino wilds, defeated and empty-handed.
Dr. Turbot and Taylor, along with the mama and baby Brachiosaurus, thanks the PAW Patrol. And Ryder tell that they should yelp for help if they have a big-dino problem. Skye, Marshall and Rex are happy that the baby Brachiosaurus have a new friend and they laugh as the episode ends.