It's Great-Great-Great-Great-Grandpa Grover Day, and Mayor Goodway has been planning anxiously for today's celebration. She sent the statue of her Great-Great-Great-Great-Grandfather, Grover Goodway to be cleaned. However, on the way back from the cleaner's, the statue fell in Adventure Bay. The PAW Patrol must dive down to the bottom to get the statue.
The episode begins with the PAW Patrol assisting Mayor Goodway with preparing for Great-great-great-great-Grandpa Grover Day to honor the original mayor of Adventure Bay, Grover Goodway, Mayor Goodway's great-great-great-great-grandfather. While all the other decorations are done, the statue of Grover has yet to show up. Mayor Goodway entrusted Cap'n Turbot to take the statue to be polished, cleaned, and returned in time for the celebration. Worried, she contacts him on his ship, the Flounder.
Turbot is on his way back right now, but the baby whale happens to appear, forcing him to avoid her. In the process, his evasive steering causes the statue to lose balance, and before Turbot can catch it, the statue falls overboard. Not wanting to worry the Mayor, Turbot keeps what happened to a minimum, and then calls Ryder to tell him the truth. When the Mayor learns of this, she grabs the Pup-Pad from Ryder and pleads to Turbot that they have to get Grandpa Grover back. Following the Mayor having a moment of amnesia in thinking she was talking to Cap'n Turbot on her own cellphone and not the Pup-Pad, she hands it back to Ryder, who assures her that the PAW Patrol is on the job.
Ryder calls the pups back to the Lookout, and while Skye flies back, the other pups run, while Marshall takes his firetruck. Marshall has a little accident when he soaks Rubble unintentionally, much to Rubble's annoyance, but Rubble forgives Marshall when he then crashes into the elevator and into Rubble himself, much to the amusement of the others. Upon reaching the tower, the orders are clear: Zuma and Skye will assist in retrieving Grandpa Grover's statue from underwater, and carry it back to City Hall. With that, Ryder, Zuma, and Skye deploy, and head for where Cap'n Turbot stopped the Flounder when the statue fell overboard.
When they reach the Flounder, Ryder uses his Pup-Pad's sonar ability to locate the statue, now resting on a rock outcropping near an underwater canyon. Zuma jokes at how the fish are gathering around the statue, and while Skye gets her sky hook ready to haul the statue up, Ryder changes to his scuba gear to head underwater with Zuma.
While getting to the statue is no problem, before they can hook Skye's hook onto the statue, the baby whale appears again, and as it passes, it hits the statue, whether intentional or not, knocking it off the outcropping, and closer to the edge of the canyon. No harm done, Ryder soon learns that the added depth is too deep for Skye's hook to extend to, and now they have to find an alternate means to retrieve the statue. Cap'n Turbot begins to panic at failing the Mayor, but Ryder realizes that they can attempt to lift the statue using a balloon and helium.
Back at the City Hall, Mayor Goodway is still panicking. Contacting Rocky, Ryder asks him to bring the helium tank and a spare balloon to the dock for Zuma to pick up. Rocky complies, and upon returning to the Flounder, while Cap'n Turbot and Skye watch with worry, Ryder and Zuma dive down, tie the balloon around the statue's waist, then fill it with helium. The plan works as the balloon floats the statue to the surface, but it soon starts to go airborne instead. Luckily, Ryder has Skye catch the rope and carry the statue back to City Hall, while he and Zuma would be right behind her once Ryder changed back to his regular clothes.
At City Hall, Mayor Goodway is still paranoid with fear, when Gustavo, Julius, and Julia arrive. She tries to figure out how to explain the absence of Grandpa Grover's statue, but as Gustavo snaps at her about Grandpa's whereabouts, Julius and Julia spot Skye bringing the statue home. When Ryder and Zuma arrive soon after, Mayor Goodway and Gustavo are proud of them from bringing Grandpa back safely and with how shiny the statue looks. Following a squid that had been on the statue since it had been underwater jumping off on Mayor Goodway's head, and Ryder collecting in a pail, the Goodways, Ryder, Zuma, and Skye, get together for a group photo with the statue.
Afterwards, after showing the photo to the other pups, Ryder lets them go have some fun since they earned it. The pups run off, barking happily, while Ryder has a final laugh to himself, before the episode irises out.