While trying to get a treat from a hard to reach cabinet, Charles, Cliff, Geo, and Walt are informed that the kids are home, prompting them to dash over to the front door, where immediately, the kids begin to lavish them with love and affection. As they play along with the pets, Lana suddenly arrives, and reveals that she found a lost dog. In an instant, the kids love it to death, leaving the four original pets disappointed.
The four pets try to get the kids' attention, but they're all too distracted giving the new dog lots of love. When bedtime comes, all of the kids want to sleep with the new dog, but Lisa says that with 11 kids, and 8 hours of sleep, each one will sleep with the new dog for an allotted amount of time. The four original pets want to substitute for the kids, but they all deny them access, obviously wanting the new dog to be with them. Fed up with the kids' attention towards the new dog, the four pets decide to hold a meeting in Charles' doghouse, where they scheme to make the kids hate the new dog.
The next day, the four pets decide to create some damage around the house, and make the new dog get blamed for it, such as breaking a vase, eating Lynn Sr.'s cooking, and track mud all over the house. However, all of these attempts only make the family love the new dog even more, since the vase that the new dog supposedly "broke" was something Rita has always wanted to do but could never bring herself to do it, the dish Lynn Sr. made is never appreciated enough, and the kids are excited to give the new dog a bath. As the pets begin to pack their bags, seemingly giving up, Charles resorts to one last tactic: call the pet sanctuary. After calling the pet sanctuary, the four pets manage to lock the new dog out of the house, allowing Schmitty, an employee from the pet sanctuary, to capture the new dog. As the pets decide to relax by watching TV, an infomercial for the pet sanctuary appears, and as they watch it, the four pets immediately begin to regret getting rid of the new dog, prompting them to hold another meeting. This time, discussing on rescuing the new dog.
After arriving to the pet sanctuary via big rig, the four pets sneak in, distract Schmitty, and manage to locate the new dog, and set it free. However, as the five pets begin to escape, Schmitty notices them escaping, but the five pets manage to escape. Unfortunately, another employee named Corinne captures them. As Corinne begins to head back to the pet sanctuary, the five pets try to escape, but Corinne tries to make them lose progress by swerving side to side, crashing the van in the process. As the pets attempt to flee, Corinne captures the four original pets, but the new dog manages to escape. After arriving back to the pet sanctuary, the new dog appears, having come back to rescue his friends. The new dog pounces onto Corinne, and manages to drive her away after chomping on her butt. With Corrine gone, the four pets console the new dog as thanks for rescuing them.
At the Loud House, the kids are making missing posters for their pets, heartbroken at the fact that they're gone. As the kids begin to cry that their pets are gone, the five pets arrive back. The kids quickly lavish the four original pets, and the new dog is allowed to join in on the hug. Just as they declare the new dog an official member of the Loud family, a young girl named Clare arrives, saying that she lost her pet dog since it slipped out of its leash. Clare sees that they have the dog, whose name is revealed to be Watterson. As Clare begins to cuddle Watterson, the kids are happy that Watterson is reunited with his original owner, but also sad at the fact that they can't keep him. Despite this, Clare applauds them for taking care of Watterson. Just before Clare and Watterson leave, Watterson decides to lick his new pet friends in gratitude. Once Clare and Watterson leave, Lincoln decides to give the pets a treat. As they eat their treats with pleasure, Lisa exclaims, "Does anyone know why my slide projector was in Charles' doghouse?!", prompting the four pets to look at each other apprehensively.
‣ Summer Swing - Marc Durst [Title card.]