In Central City, siblings Andi (Emma Roberts) and Bruce (Jake T. Austin) defraud a pawn shop owner to raise money to feed their Jack Russel Terrier, Friday. Soon afterwards, the pawn shop owner approaches them with a police officer, pointing Andi out as the culprit. As she tries to talk her way out of trouble, Bruce’s backpack falls and its contents spill out, revealing his scamming supplies. They then are arrested and taken to the local police station, where their social worker, Bernie, sternly scolds them and says that they may be separated the next time they do so because they keep changing from their previous foster homes to another. Bernie then takes them home to their foster parents, aspiring rock stars Lois and Carl Scudder. The two are angry that the children have missed dinner (and delayed band practice) and Bernie takes responsibility. Andi and Bruce are sent to their room for the night, where they have hidden Friday from their guardians.
In the morning, Friday wanders out of the room into the apartment and is almost seen by Lois. The kids attempt to get him back into their room, trying to hide what they are doing, and eventually do so without Lois realizing what is going on. Once back in the room, however, Friday uses a homemade elevator, designed and built by Bruce, to leave the apartment through the window and is picked up by animal control. Andi and Bruce are desperate to find Friday and scour the area looking for him. They enter a pet store and ask the manager, Dave, and employee Heather, whether they have seen Friday. Neither of them has, but they suggest visiting the local pound to see if he is there.
At the pound, Andi and Bruce discover Friday is indeed there, but must bribe one of the officers to get him released. On the way home, they encounter a burglary in progress at a store and as the police arrive they flee to a nearby abandoned hotel to avoid being pointed as the culprits. Friday then gets away from them again and they search the building to find him. As they do, they hear strange noises, which they discover to be a brindle English Mastiff and a French Bulldog puppy that have taken shelter inside the hotel. With them is Friday a jack russell terrier, and Andi and Bruce decide to leave him in the hotel for the night and return home.
The next day, the two kids steal from the refrigerator to take to the hungry dogs. At the hotel, they find that the mastiff was howling because the shades had been drawn. The kids return to the pet store to get more food, and lie to Dave, claiming that their parents are dog rescuers. Heather follows them back to the hotel and announces that she wants to help. They are later joined by another kid, Mark, who has a crush on Heather. Bruce builds a number of contraptions to keep the dogs fed and entertained while they are alone in the hotel. They decide to take in all the stray dogs they can find. Bruce begins to name all of the dogs and keep track of them in an old hotel guest registry.
Andi sneaks out of the apartment and goes to a party she was invited to attend. However, she is recognized by Dave’s best friend, Jason who tells Dave and Heather that she is actually a foster child. Upset, she runs from the party to the hotel, where the dogs are running wild. The police come to the hotel, arresting the kids for trespassing. The dogs end up in the pound. Bernie and his wife, Carol, tell them that there is nothing more they can do. The dogs are scheduled to be euthanized and Andi and Bruce are sent to separate foster homes. Meanwhile, in the animal control station, Friday escapes from his leash and runs to Dave. They pick up Andi and Bruce, sneak into the pound, and release the dogs, attempting to lead them to the truck with some sausages, but the dogs go to the hotel which Bruce realizes is because it’s their home. As they pass the hotel, however, the dogs run inside and a standoff ensues with the police and an animal control member tells the police to arrest Andi, Bruce, Dave, and Heather. Bernie gives an emotional speech about the dogs’ never-losing hope after their negligence from their human owners, causing the media and some of the police to look at what the kids have done to the hotel to see about the dogs staying there. Exasperated with no dog-catching action, the animal control workers run off outside.
Bernie and Carol end up adopting Andi and Bruce themselves and love dogs so they have no problem with the kids keeping Friday. In the meantime, Andi and Dave start dating and Mark finally impresses Heather and she kisses him on the cheek. Pressured by the media at the scene, the police are persuaded to allow the dogs to remain at the hotel, which is eventually restored as a community-funded, full-fledged canine retreat where the kids and even some of the dogs work. The new hotel is like a real hotel with restaurants, entertainment, a salon, adoption, bellboys, rooms, massage and more. Andi and Bruce’s former foster parents, Carl and Lois, are part of the entertainment, but perform so terribly that even the dogs get bored of them.