Cap'n Turbot accidentally stumbles into a secret cavern that was once a pirate's hideout. When the PAW Patrol rescued him, they find an incomplete treasure map. The adventure is on as the pups follow clues to find the missing map pieces, and eventually to an amazing sunken pirate treasure!
The episode opens with Cap'n Turbot attempting to get some pictures of the blue-footed booby bird again, this time with its eggs. He is just about to take the first photo, when the booby bird attacks him in defense of its eggs. As Turbot steps backward trying to explain himself, he falls down a hole, and ends up stuck in a barrel in a cave underneath. After pulling himself out, and finding the beach crab clamped onto his behind, he finds a chest, along with a black flag sporting the all-too familiar Jolly Roger skull-and-crossbones. Turbot immediately suspects that the cave was a hideout for the legendary Adventure Bay pirate, Captain Blackfur. With him pretty much stuck, Cap'n Turbot calls Ryder for help.
At the Lookout, Ryder is playing basketball with Marshall, Chase, Rubble, and Zuma. Marshall is having a lot of trouble making a basket, as every time he misses, he hits Rubble afterward. After it happens again, the pups head off to find a means to help Marshall out, while Ryder gets Cap'n Turbot's call for help and his hypothesis that he may have stumbled onto Captain Blackfur's hideout. Excited to find some more evidence to Captain Blackfur's existence, Ryder contacts the pups and has them report to the Lookout. Marshall and the others have chosen Rocky's catapult to help Marshall with making a basket, but Ryder's summon causes Marshall to fall on the catapult after the basketball was launched, and the ball activates the catapult, sending Marshall flying into the elevator ahead of the other pups. After Skye reprimands Marshall about how she's the flying pup, and he is more than happy to accept that, the pups report upstairs, and are excited at how they might be hunting for pirate treasure, especially Rubble. Ryder picks Chase and Rubble to assist with helping Cap'n Turbot, and the team heads out to where they last knew of Cap'n Turbot's whereabouts.
When they arrive, he gets their attention, and Chase uses his winch to lower Ryder down into the cave so the Cap'n can show him the pirate paraphernalia he found. Afterward, Ryder has Rubble and Chase come down to join him, even though Rubble is suffering another panic attack from his arachnophobia, since caves are one place where spiders live. After Rubble gets spooked by one, Chase joins them, and Ryder has Rubble try on an old pirate hat that fits Rubble perfectly. Afterward, Chase finds another opening that is blocked by a large rock and a pile of smaller ones. He can smell seawater from outside, and it is not long before Rubble manages to clear away the smaller rocks so they can get to the larger one. Chase then hears distant waves crashing, and Ryder decides to call in Zuma to check to see where they are going to emerge. Luckily, Zuma arrives to point out that the others will emerge on the North Shore Beach, and together, Ryder, Rubble, Chase, and Cap'n Turbot are able to push the large rock aside and get out. Soon, they find a message in a bottle, and realize it is part of a treasure map from Captain Blackfur. Ryder calls Marshall, Skye, and Rocky back at the Lookout, and has them meet up with the others. When they arrive, Ryder reveals the map, but points out that there is no "X" marking where the treasure is. However, he does find a cryptic message from Captain Blackfur, saying that he broke the map into three pieces, and they can find the second piece in the mouth of the rock outcropping shaped like a parrot's beak.
The team sets off to find it, while Cap'n Turbot stays behind, disappointed over how the pups get all the excitement and fun out of missions. Skye soon gets to the location first, but finds a little bunny rabbit sleeping on a rock. Soon, the mama eagle appears overhead, and fearing that the little rabbit will be the Mama eagle's next meal, Skye takes flight with her pup-pack to lure the Mama eagle away, giving the rabbit time to wake up, realize the danger, and hop to safety. As for Skye, she is soon in a dogfight with the Mama eagle, but finally manages to lose her, just as the rest of the PAW Patrol arrive. Once they regroup, they soon see the bottle right where the map piece said it would be, and Skye retrieves it. Afterward, Rocky tapes the two pieces together, and the clue from Captain Blackfur on the second piece says that the third piece is located in a knothole of the largest tree in Adventure Bay. Chase realizes that the trees where his owl friend, Little Hootie, lives are full of knotholes, so the last piece must be in one of them. The team immediate set out for the forest where Little Hootie lives, though Rubble nearly gets left behind when he starts acting like a pirate again and does not notice the others leave until a moment or two later.
Skye, Zuma, Rocky, and Rubble are the first to get there, but Rubble's first attempt within a large tree trunk due to his bravado only gets him a spider on his nose that Rocky removes with a shovel from his pup-pack and puts back, revealing that a whole family of spiders lives in the hollow trunk, much to Rubble's disgust and paranoia. Skye's attempt only sends her reeling, pup-pack first, backward against another tree from a sneeze induced by the dust in the knothole she checked. Soon, Ryder, Marshall, and Chase arrive, and Little Hooty comes down to see what's happening. Chase asks Little Hootie if he's seen a bottle in any of the knotholes, and Little Hootie flies over to the knothole where the bottle is located. Marshall drives over to retrieve it with his ladder, but loses his balance and nearly lets the bottle smash on the ground. Luckily, Ryder catches him, and Marshall catches the bottle in his fireman's helmet. After thanking Little Hootie for his help, Ryder has Rocky tape the third piece to the other two, completing the map, and find the "X" that marks the spot.
According to Captain Blackfur's instructions, you were to walk 20 paces from where you found the last piece of the map, but Ryder only gets about halfway before he discovers if he went any further, he'd fall into the ocean. Ryder thought that the map was wrong. However, Marshall took tiny steps which was consistent with the map's instructions, yet he nearly sent Ryder over the cliff because he was counting too fast. That's when the PAW Patrol spot something anchored on a small island just a short distance from the cliff, but obscured by an eerie, green fog. When Skye flies over to investigate, she discovers it to be Captain Blackfur's old pirate ship. Age has really done a number on the old vessel, as it looks like it is ready to fall apart when the tide changes. Knowing they can't let that happen, the PAW Patrol set out to save the old ship.
While Skye attaches a mooring line to the mainmast, Rubble digs out a channel to bring the ship to the mainland, and Chase has his winch attached to the front of the ship to help Skye pull it in from the small island it's on. Ryder and Zuma overlook the rescue effort from their hovercrafts, and at first, things seem to be going fine. That is, until the ship's anchor chain goes taut, indicating the anchor must be stuck on something underwater. Ryder and Zuma head down, and find the anchor is indeed stuck between a pair of rocks. When the anchor won't budge upon trying to free it, Zuma kicks his pup-pack's scuba engines into overdrive to provide him the thrust to push one of the rocks out of the way, freeing the anchor, and allowing the ship to resume being pulled to shore. As the other pups cheer, Ryder and Zuma surface to notice a rope ladder dangling off one side of the ship's stern, and decide to climb aboard for a ride.
It is soon sunset, and Cap'n Turbot, Mayor Goodway, Chickaletta, Mayor Goodway's niece and nephew, and several citizens, are waiting when the PAW Patrol arrive with Captain Blackfur's ship safely intact. After the Mayor makes a short speech about the PAW Patrol saving a valuable piece of Adventure Bay's history, Ryder invites Cap'n Turbot aboard via Marshall's ladder to help with hauling Blackfur's treasure up from the cargo hold. Once they have it topside, Rocky provides a key to undo the chest's lock, and upon opening it, Ryder, the pups, and Turbot, are amazed by all the gold doubloons, gems, and other treasures inside, such as golden dog bones, and a golden, jewel-encrusted dog bowl. At first, they think that Blackfur had a faithful pirate pup, until they find a portrait of the legendary pirate himself, and discover the Blackfur was a pirate pup. Even more interesting, he looks to be a distant ancestor to Rubble, due to the similar appearance between them, save for Blackfur's trademark black fur beard. Blackfur also left a message requesting what to do with his treasure once it was found. According to his last requests, once his treasure was found, Blackfur wanted it to be returned to the good people of Adventure Bay.
With that, the episode ends with a pirate-themed version of the PAW Patrol ending theme, as the pups enjoy playing around Blackfur's ship, and Marshall landing next to Rubble, who now sports a black fur beard just like Blackfur, leaving both to laugh as the episode irises out with a skull-and-crossbones iris out to go with the pirate theme of the episode.