Not much is known about Ewan except that he was a recently released ex-convict having served his sentence for an unknown crime. After his release, he began working at Kevin Shepherd's 2nd Chance dog shelter.
Ewan is first seen arguing with his probation officer Chloe Simon about his missing pay stubs, which the former claims that they were eaten by a dog. When Chloe warns him that he will not get any probation if he doesn't turn in any pay stubs, Ewan takes out a lot of stuff from his leather jacket, including a picture of him with Kevin and The Gang in front of the dog shelter, until he produces an I.O.U. (that Drooler happened to "[get] a hold of"). Chloe reluctantly gives him the probation but warns him to have pay stubs for their meeting next week. Before leaving, Ewan tells Chloe to keep the photo.
Ewan later returns to the dog shelter just in time to see Kevin begin humiliated during a game of Tug-O-War against The Gang and teases the former for once again "fall[ing] for that one". While feeding the dogs with dog food that Ewan picked up, Kevin question Ewan on if he "pinched" the dog food, but the latter denies it. After the feeding, Kevin asks Ewan to save some food for tomorrow since he doesn't know where the next meal's coming from, which Ewan responds by saying that his mother always said, "When the heart hopes, hope comes knocking." (Shortly afterward, there IS a knock on the door, but it is actually the debt collector Mr. Bucket who came to shut down the shelter.)
The next day, while the dog shelter attempts to stop their final eviction from Mr. Bucket, Ewan points out that the press has arrived (who have actually arrived to report that Cruella De Vil has arrived to save the dog shelter).
The following day, during the beginning of 2nd Chance's renovation, Ewan is seen playing in a junk airplane and pretending to be the Red Baron, when Kevin asks Ewan to stop playing and help out. When Chloe (also the probation officer of Cruella) arrives, Kevin mistakes her for another volunteering assistant and even falls in love with her, but Ewan tells Kevin that she is his probation officer and quickly hides. As Chloe asks Kevin for his name and if he's a "dog lover", Ewan points out that he is, but Chloe tells Ewan that she will get to him later and asks for Cruella, which Ewan points out to be in the back.
After the new 2nd Chance dog shelter is finished, Ewan and Kevin are shown to be introduced to the new inside by Cruella, and then "showering" themselves with a ton of letters full of donation money.
A few days later, Kevin gets a call from a mysterious man with a French accent about a box of abandoned "poopies". Kevin sends Ewan to rescue the puppies, but when Ewan returns, he discovers Kevin in handcuffs by the police and denies his involvement in the crime he might be accused of, but Kevin explains that he sent Ewan to pick up the box. Kevin and The Gang are sent to jail for dog-napping Dalmatians (in reality, though, they were being framed by a once-again-corrupt Cruella De Vil), but Ewan's fate remains unknown.
At the end of the movie, Ewan is seen celebrating with Kevin, The Gang, Chloe, and her Dalmatian family about being awarded Cruella's fortune, as well as Oddball finally getting her spots.