Lincoln and Clyde are hanging out at the Loud House, watching the Swarm of the Zombies movie marathon. Just when Lincoln and Clyde prepare to the remaining four movies in the series, Lynn Sr. tells the boys that they need to head to bed. Upon entering Lincoln's room, Lincoln reveals that he knew that they'd be sent to bed at this moment, and says that he plans to watch the marathon in Lisa's underground underground bunker. After pulling out the inflatable exit slide, Lincoln and Clyde proceed to watch the remaining movies, which takes the entire night.
Once the fifth movie ends, Lincoln and Clyde quickly exit the bunker and enter the house. To their discovery, the interior of the house is in ruins, everyone is missing and the power is out. After searching around some more, the boys discover that every house is in the same condition: the interiors are in ruins and everyone is missing. Lincoln assumes that they woke up in a zombie apocalypse, but when Clyde comments that it's not an apocalypse unless there's a zombie, they suddenly spot a silhouetted figure approaching, causing the boys to believe that they are in a zombie apocalypse, and run away into a hiding spot. Seeing the dangerous situation they're in, Lincoln suggests that they head to their secret hideout.
While trying to avoid being caught, they approach the Burpin' Burger for a bathroom break. While doing so, they suddenly hear noises and realize that there's another zombie present. They quickly slow it down by dumping garbage on it while they escape through the window. Heading to Flip's Food & Fuel, they attempt to stock up on supplies, but they hear Flip from the office, but discover it's actually just a recorded voice on a walkie-talkie. At that moment, they hear a noise and discover a zombie lurking in the store. The boys manage to stop it by dumping nacho cheese on it. At Tall Timber's Park, Lincoln and Clyde enter their secret hideout and turn on the radio in hopes to find contact. On the radio, Mayor Davis tells the listeners that if they are still outside, everyone is congregating at the Royal Woods Mall. Realizing that they're not the only survivors, Lincoln and Clyde proceed to head to the mall.
After exiting their hideout, Lincoln and Clyde attempt to head to the mall, but have to fight the zombies on the way. The boys manage to completely get them out of the way by tricking them to go in a dumpster and rolling it away. As they approach the mall, the dumpster suddenly hits a roundabout, causing it to head towards the boys. Fearing that they doomed their parents, Lincoln and Clyde proceed to fight back by using water guns filled with juice, and when they run out, the proceed to fight them with hand-to-hand combat. Suddenly, Rita tells the boys to stop, saying that they're beating their fathers. After a closer look, it turns out that the zombies were Lynn Sr., Harold and Howard all along. They explain with raspy voices that last night, Mayor Davis warned of a terrible storm approaching and urged all Royal Woods citizens to hang out at the mall for safety. While the sisters, Rita and Lynn Sr. got the message, Lynn Sr. states that he and the McBrides will try to find the boys while Rita takes the girls to the mall. With the truth revealed, Lincoln and Clyde explain that they were in Lisa's bunker at the time, and Rita initially intends to punish them for sneaking out like that, but believes that the suffering they went through today is punishment enough (much to Lynn Sr.'s dismay, since he and the McBrides suffered numerous injuries due to Lincoln and Clyde attacking them). Lincoln and Clyde apologize for the mix-up and for hurting them at all the locations they went, like the Burpin' Burger, Flip's, Tall Timber's Park etc. However, the dads remark that none of them went to Burpin' Burger. This causes everyone to believe that there really was a zombie lurking.
At the Burpin' Burger, it turns out the "zombie" at the restaurant was actually Flip, who was using the town-wide panic/storm commotion to get free burgers with nobody being the wiser.