Spoiler warning! This section contains plot details about an episode.
The episode opens with Dylan in a video game-like fantasy, shooting pink goo left behind by the pups. We see that the reality is just him cleaning the house with a vaccuum cleaner as pups leave muddy footprints on the floor. He hears a laugh, and sees Dolly slide down the stair railing yelling with delight. He remarks that she is not helping, to which she insists that she is polishing the banisters. She says she "missed a spot...again" and slides down one more time, with the other pups watching her intensely as she barks her catchphrase. Dylan is trampled by the pups as they follow Dolly, messing up the house again.
Delilah yawns, likely just woken up, and dodges the onslaught of pups as she wishes Dylan luck with the chores. She leaves for work just as Doug returns from his night shift, covered in soot. Delilah barely escapes out the door to avoid getting trampled by the pups greeting their father. Dylan complains about the mess as the soot billows off of Doug onto the floor.
Dylan is wiping the windows clean as he sees Clarissa's human vaccuuming the floor as her every need is tended to. Dylan laments about not having a human "pet" to do all of the chores for him. Dizzy and Dee Dee heard his complaints, and decide to take it upon themselves to go find a human. They arrive at a coffee shop (which they call "The Pet Shop") and survey a few humans from afar. They find Mr. Fuzzy, swiping on his dating app looking at girls in the area. He is sad about being unsuccessful until he sees Dizzy and Dee Dee barking and trying to bring him home.
We cut back to the house with Dylan finishing up the floor, being ushered to open the door. Dizzy and Dee Dee show Dylan the human, to which he insists that the human must leave and that he cannot be in the house. The other pups are enchanted by Mr. Fuzzy, but Dolly is skeptical. Dylan tries to tell Mr. Fuzzy to leave, but is distracted by his tummy being scratched. He then sees Clarissa's human serving her some ham on a platter, and decides a human might not be a bad idea, perhaps even educational for the younger pups. Dolly accuses Dylan of just wanting someone else to load all of the chores onto, and he retorts that Dolly isn't much help in that aspect of the house either.
We cut back to the inside of the house where Mr. Fuzzy is using the restroom, which the pups have been using as a water bowl. Dylan thought he was using it as the rest of the pups have been, but is informed that he is using it for other purposes, to which he coos and says he is "marking his territory". Both Dylan and Dolly are disgusted when they open the room and Dolly remarks that she's not touching that "drinking bowl" again.
Mr. Fuzzy is admiring the portraits on the wall and states that whoever must live in this house is "dog crazy", and then jokes that it might only be the dogs who own the house. He discovers the kitchen and the stroking machine the pups have made, and bumps into it. This grabs the attention of Dylan, who attempts to stop Mr. Fuzzy from creating a mess. Mr. Fuzzy turns on the machine, and is caught as it turns and gets thrown across the room into a pile of toys. Dylan scolds Mr. Fuzzy as Dolly, Dee Dee, and Dizzy laugh at him. Dolly remarks that she could start to like Mr. Fuzzy. Dylan is upset until Mr. Fuzzy starts petting his ear, and he decides that they may not need a stroking machine if there is a human to pet them.
Dylan decides to start to train Mr. Fuzzy, so he brings him a vacuum cleaner and turns it on. Mr. Fuzzy gets tangled in the tubes and trips over, earning a facepaw from Dylan. Dylan makes several attempts to get him untangled and starting to clean, to which Dolly chuckles at. Dylan ends up dirty and dazed, and disenchanted with his task until Mr. Fuzzy begins to vacuum the floor. Mr. Fuzzy vacuums up a squeaky toy, which causes a puff of dirt and smoke to come from the vacuum, covering Dylan.
Dylan tries to teach Mr. Fuzzy dishwashing next, so he puts him in front of the sink with a bottle of soak. Mr. Fuzzy is intimidated by the large pile of dog dishes, and starts to slide pups on a stream of water instead, one of which knocking Dylan over. He hands Mr. Fuzzy a mop and tries to clean up the mess, but while Dylan is stuck cleaning, Mr. Fuzzy dances with the mop. He dances up the stairs and smacks into a closet door, which opens up and releases a slew of squeaky toys down the stairs.
The commotion wakes up Doug, who discovers that the pups have let a human into the house. Dylan admits it was his fault, and Doug begins to lecture him on the ages of humans and the responsibility that they can entail. Part of his lecture is that you need to walk them in the park, "park" being a trigger word, and we are wiped to the park.
Dylan is walking Mr. Fuzzy on a leash, while Mr. Fuzzy is tapping away on his phone. Mr. Fuzzy is distracted by a shop vendor, the same girl he saw on the dating app in the coffee shop. Dylan, frustratingly trying to teach him fetch, takes his phone and throws it, prompting a chase between him and the pups.
We cut back to the house, with Mr. Fuzzy surrounded by the pups as he tries to nap. Dylan falls asleep, and wakes up to find that the kitchen is a mess. Mr. Fuzzy has messed up the food machine and is being flung by the tip of the hose, food going everywhere. Doug is trying to calm the pups down until he gets coated in food. Dolly and Dylan are able to shut it off, and then Mr. Fuzzy is scolded by Dylan. He gets his head stuck in a wall, and is heartbroken when his phone screen is cracked. Doug tells Dylan that he needs to put Mr. Fuzzy back "with his own kind", even if it breaks [his] heart". Dylan is inspired by this phrase, and has a plan to make Mr. Fuzzy happy again.
Dylan steals his phone and brings it to the park, dropping it in front of the Vendor from earlier. The vendor sees that Mr. Fuzzy matches a picture from the same dating app he was on, and the two stare into each other's eyes as Dylan starts crying as Dolly and the dalmatians comfort him.
In the UK and Ireland, "Dog's Best Friend" premiered on December 14, 2018 on Disney Channel at 4:31 PM. In the Middle East and South Africa, the episode premiered on the same day at 7:30. In Germany, the episode premiered on the next day at 10:55. In Belgium and France, the episode premiered on December 16, 2018 at 4:30 and 10:55 respectively. In the Czech Republic and Hungary, the episode is set to premiere on December 21, 2018 at 18:30. In Poland, the episode will premiere on the same day at 18:30. In Spain, the episode will premiere on the next day at 11:10.