Trouble is a pampered dog living the good life in a mansion with his elderly wealthy owner, Mrs. Sarah Vanderwhoozie under the care of her loyal butler, James and famed animal trainer, Cesar Millan. One day, his owner dies due to natural causes and is left alone in the mansion, unaware of her death. Then, Claire and Norbert, Mrs. Vanderwhoozie's greedy niece and nephew arrive to claim their inheritance. However, while getting rid of some of her belongings and planning to sell some that are priceless, they accidentally and unknowingly get rid of Trouble as well, whom they show instant dislike and apathy towards. Nevertheless, in order to rightfully inherit their aunt's fortune, Claire and Norbert must first be willing and able to bond and take care of Trouble within three days until they can sign the contract entrusted by their aunt's lawyer, Mr. Macbain; much to their reluctance. Realizing that Trouble is missing, they hire Thurman Sanchez, an expert animal tracker to find him in time before the deadline.

Having made it out of the truck carrying away his owner's belongings and after learning the truth about her, Trouble accidentally messes up a group of squirrels' nut storage in their tree. As payback, the squirrels steal his collar and run off, leaving Trouble lost and alone like a stray. In the city, Trouble meets a stray dog named Rousey while trying to get a meal from a meat truck, which results in a chase through a restaurant owned by famed chef, Ludo Lefebvre and a singer-wannabe pizza girl named Zoe Bell losing one of her pizzas during a delivery. After another encounter with the squirrels and spending the night with Rousey in the outdoors, Trouble enters a dog park where he meets domestic dogs: Norm, Gizmo, Bella, and Tippy who somewhat help him find a home by having him play in traffic, get picked up by Zoe, and taken to her apartment. Though only temporary until she can find where he belongs while avoiding her landlord from finding out, Zoe and Trouble begin to bond as Zoe writes her song for a singing competition and fashions a new collar for Trouble.

The next day, at the dog park, despite rocky first impressions, Norm and the other dogs willingly help Trouble out when they find out that the squirrels took his old collar while confronting him again. During the struggle, Thurman, having found Trouble at last, accidentally snatches the leader of the squirrels, whom he offers to make a deal with; a pile of nuts in exchange for their help in retrieving Trouble for him. After Zoe momentarily leaves Trouble at her apartment, the squirrels try to flush him out of the apartment while causing a huge mess, which results in Zoe being evicted by her landlord when she returns and Trouble sent to the dog pound where he meets Rousey again and befriends other dogs: Snoop, Otis, and Caramel. Trouble learns from Rousey that she was once an indoor dog much like himself until one day, after saving her owners' kid from a traffic collision, she was mistaken for harming him and later dumped at the pound, which explains her distrust of humans.

On the day of the deadline, rather than to enter the competition, Zoe decides to go to the pound and retrieve Trouble but Thurman has already beaten her to it, so, she rides off looking for him all over the city. Realizing how much Zoe truly loves and cares about Trouble, Rousey decides to help the others escape and help Zoe find him using his new collar left behind to track him and with the help of the domestic dogs as well. After Thurman returns Trouble to Claire and Norbert at the mansion, he secretly vows retaliation with the squirrels' help when the twins refuse to pay him as promised.

Claire and Norbert are about to claim their inheritance after falsely leading Mr. Macbain to believe that they actually bonded with Trouble until Zoe suddenly arrives and reveals what really happened. Then, Thurman enters and demands his money as he further reveals the situation to Mr. Macbain. Having learned the truth, Mr. Macbain denies the twins' inheritance. Still wanting his money, Thurman summons the squirrels to hold Trouble for ransom until Snoop, Otis, and Caramel, having followed Rousey, enter and a battle ensues. When Trouble is held under threat against a fan by the squirrel leader, Rousey arrives just in time to save him and demands Trouble's old collar back before the squirrels exit. Trouble is then granted permission by Mr. Macbain to decide whom he wants his owner to be and joyfully chooses Zoe, which allows her to inherit both Trouble, the mansion, the assets, and the fortune after signing the contract; much to the twins' disgust as both they and Thurman leave. Rousey is also adopted by James; much to her joy.

Zoe uses the money to renew the dog park renamed The Vanderwhoozie Dog Park dedicated to both Mrs. Vanderwhoozie and Trouble and begins living her dream as a singer, which attracts the attention of famed singer-songwriter, Jason Mraz. Then, Snoop, having probably been adopted along with Otis and Caramel by Zoe as well, proceeds to sing in dedication of Trouble; much to the dogs' joy.

See also
The Chain Reaction (The Fixies)
Hair Love (Full-length cartoons)
The String Light (The Fixies)
Tracks of unknown Animals (Episode 4) (Masha and The Bear)
The Cartoon (The Fixies)

Trouble - watch online