Up at a summer camp, Ms. Marjorie and Maynard are passing out books to the kids and Everest from her bookmobile before setting off to return to Adventure Bay. However, when Ms. Marjorie decides to relax in the back with a book she becomes interested in, Maynard accidentally releases the emergency parking brake as he climbs into the passenger seat, leaving the bookmobile to roll away. This attracts Everest's attention and she also sees Maynard attempting to steer it while Ms. Marjorie was unaware. Worried, Everest contacts Ryder to let him know of the situation.
At the Lookout, Ryder is reading a story to the pups when he gets Everest's call for help. Alerted on the situation, he summons the pups to the Lookout. Once topside, Ryder assigns Everest, Skye, and Chase to aid in stopping the Book Mobile. The team deploy and head out.
When they reach the bookmobile, Chase drives ahead to clear the road of traffic. Ms. Marjorie soon discovers what was going on upon several bumps getting her attention that the bookmobile was moving once she was done reading, and lets Skye airlift her to safety. She drops her off on a patch of grass nearby when suddenly, books start falling out of the Book Mobile. Ryder realizes this and summons Rocky and Rubble to help in saving all of Ms. Marjorie books alongside Everest.
However, as Chase drives ahead to clear the road, he is forced to a stop at a railroad crossing as the crossing's red warning lights were flashing and the bells ringing, indicating that a train was coming. The gates then lower to bar any vehicles from getting stuck on the tracks and hit by the train. Chase, unable to move forward, warns Ryder of the oncoming train. With quick thinking, Ryder sets his ATV to autopilot and climbs aboard the bookmobile to stop it before it hit the train. He tries the brakes, but they are not able to slow the bookmobile down due to wear and tear. He also tries to rearm the emergency parking brake, but to his dismay, its handle breaks off. With time running out, Ryder has Rubble and Rocky to use some leftover I-beams or rails to form a ramp where he could use it to launch the bookmobile over the train and land it safely on the other side. With lady luck on their side, they pull through the situation safe and sound, regrouping when the train has passed.
Ms. Marjorie is grateful for the PAW Patrol's help, but just before she finished her sentence, the bookmobile falls apart from all the damage and age catching up to it. Luckily for Ms. Marjorie, the PAW Patrol are able to rebuild it better than ever, allowing her to return to the summer camp to not only show off her new bookmobile, but also deliver books to the kids and Everest again, making it a very happy ending.