Miles away from Adventure Bay, on the volcanic Rumbletop Island, the Turbot cousins are looking for the Rumbletop White Tigers that are native to the island. Unfortunately, the cousins are once more arguing over who's in charge of recording the find and finding the tigers themselves, so it is making it harder for them to find the tigers.
Meanwhile, back in Adventure Bay, the pups are playing with Julius and Julia, when Julia's kite gets stuck in a tree. The pups attempt to get it down via stacking top of each other, but Marshall knocks the tower over. However, he is able to use the tire swing to swing up and reach it.
Back with the Turbots, they soon reach high ground and stop for lunch, but a loud rumbling causes them to start bickering again, with Francois blaming Horatio for having them come out to the island for nothing. While they argue, a mother tiger and her cub, resting on an outcropping above, are unseen to them. The cub soon wakes up, and spotting the Turbots' backpack they had dropped, it climbs in, resulting in it being carried off by them as they go to investigate the rumbling, still arguing. When the mother discovers this, she takes off in pursuit. This results in where the Turbots soon discover the mother stalking them, unaware of the cub being in their backpack. When they slip down a short, steep incline, leaving them unable to get back up and out of the cave, Cap'n Turbot calls Ryder for help.
Back in Adventure Bay, Ryder gets the Captain's call for help, but the mother tiger and more rumbling causes him to lose his cellphone down a nearby hole where it lands out of reach on a lower level, while the Turbots end up sliding down deeper into the mountain's cave system when the mother tiger attempts to get her cub back from them again, and results in them getting split up from each other, with the mother taking off in pursuit once she has her cub's scent. Having lost contact with the Turbots, Ryder summons the pups to the Lookout for an Ultimate Rescue.
After Marshall crashes into the elevator with the tire from the tire swing and jokes about it, the pups head topside, as they do, the PAW Patrol shield on the Lookout changes to look identical to Skye's badge, the lights circling the top of the Lookout now flash pink, and even the elevator and briefing screen are given pink highlights. The pups themselves find they've been decked out in aviator suits, as Ryder appears sporting his own suit, and reveals their latest Ultimate Rescue to be one with Skye in charge with traveling to Rumbletop Island to rescue the Turbots. After Ryder passes out orders and assigns Skye as the leader of the mission, he heads down the fire pole, while Skye heads down to board her helicopter. Once she's in the driver's seat, like with Chase before her, her partially-transformed helicopter is lowered into the underground maintenance room to be outfitted and transformed into its Ultimate Rescue form, which bears some similarities to the CH-46 Sea Knight and CH-47 Chinook helicopters with twin top-mounted rotors, one rotor being part of a separate mini-copter, and additional wings and engines. Once outfitted, the Lookout rises to allow Skye to drive the Ultimate Copter out onto the driveway for the pups to mount up in, with Chase riding up front with her, Marshall in the mini-copter, and Rubble, Rocky, and Zuma hooking up in the open mid-section for rapid deployment. Ryder roars out of the garage on his ATV, repainted in the colors of Skye's helicopter, and converts it into a new, helicopter-like setup to fly with Skye to Rumbletop Island.
As they arrive over the island, they spot Wally relaxing in the back of the Flounder and acknowledge him before beginning their search for the Turbots. They soon locate the video camera the Turbots had dropped earlier, and after Chase, Marshall, Rocky, and Rubble parachute down from Skye's Ultimate Copter, joined by Ryder on his ATV, they soon begin to wonder where the Turbots are, along with the tigers.
Meanwhile, Cap'n Turbot tries looking for Francois, only to soon find him, and learn of why the mother tiger was after them earlier when the cub reveals itself to them. Both Turbots take a liking to the cub, but when the mother comes looking for it again, the Turbots soon discover the reason for why the mountain had been rumbling earlier as they arrive in the magma chamber, full of bubbling hot lava, and realize that Rumbletop Island's mountain is an active volcano that's about to erupt. The mother tiger and her cub are reunited, but unfortunately, Francois is unable to resist the urge to tempt fate by saying at every opportunity "Could this get any worse?!" This results in the tigers being separated when the rock platform they are on cracks apart, splitting the mother off from her cub as both float out into the lava lake, while the Turbots hug each other for comfort as they suffer a similar fate.
The pups and Ryder soon find Cap'n Turbot's phone, which Rocky retrieves with his rappelling gear, while Rubble finds some squid jerky. Chase's allergies indicate the whereabouts of them along with the tigers, but they soon learn the truth once Skye notices steam being emitted from the volcano along with the rumbling, and realize it is about to erupt, and the tigers and Turbots are trapped in the magma chamber, unable to escape. Despite Marshall's fear of tigers and the volcano about to blow, he and the other pups brave parachuting into the volcano's mouth to locate and rescue everyone after returning to the Ultimate Copter under Skye's orders, while Zuma and Ryder follow the trail of steam from the cave they're in to locate the magma chamber as well.
They soon create a means to escape the magma chamber, and using their pup-packs, such as Marshall using his water balloons to cool the rocks from being heated up by the magma, Chase deploying a trampoline, Rubble using his shovel, and Rocky using his rappelling gear, they are able to provide a means to help Cap'n Turbot get to safety, while Zuma and Ryder rescue Francois and the mother tiger. Skye puts her Ultimate Copter on auto-pilot to travel down in the mini-copter to rescue the cub. However, after she returns safely to her Ultimate Copter with the cub, it is discovered that another rumble prevents everyone from escaping the magma chamber now. Ryder can't fly everyone out on his ATV in time, so it looks like they are trapped with the volcano about to blow any second. Francois tempts fate again, and the Cap'n tells him to stop saying that.
Seeing everyone in trouble, Skye moves in with her Ultimate Copter to save them with the cub riding shotgun as she does. Back with everyone else, despite Cap'n Turbot telling Francois to keep his mouth shut and not tempt fate again, Francois brushes him off and is about to say "Could this get any worse?!" one more time, but the arrival of Skye in her Ultimate Copter causes him to change the last word to "better?" as they realize Skye has arrived to get everyone out just in time.
Everyone loads up into the Ultimate Copter, and with Ryder alongside on his ATV, Skye is able to navigate it out of the volcano and put some distance between the mouth and her just in time as the volcano sends a plume of ash and lava into the air, which everyone stares at in amazement. Ryder commends Skye on a job well done.
Later on, back at the beach with the Flounder, Ryder and the pups look at Rumbletop as it lets off one last belch of steam before going dormant again. Meanwhile, the Turbots are spooked by the tigers again when they think the mother is going to attack them again, but as they then finish their recording of meeting the tigers, the cub causes Francois to bump into Cap'n Turbot, resulting in the camera smacking against a rock and breaking apart, ruining their footage. The Turbots can only say together in disbelief and annoyance, "Could this get any worse?!" Ryder and the pups can only laugh in amusement.