Barko was once a great sled dog and "champion of all the North". However, as he reached old age, he became unwanted and stricken with rheumatism. He spent most of his retirement at a hardware store that used to rent/sell sled dogs.
It wasn't until the crooked Soapy Slick threatened to take the fortune of Scrooge McDuck because of an I.O.U. from 1898 that Barko was needed. Scrooge had proof through a receipt, but because of a fight upon the plane with a disguised Slick, Scrooge's bag (along with the receipt inside) fell near the Frozenjaw River. Scrooge needed a sled team fast, but the only good team left was in Slick's possession. Upon seeing that the only two dogs left were "Kyoodles", Scrooge then discovered Barko in the snow. The two instantly befriended each other, and thus, the quest began.
The team soon caught up with Slick's team, thanks to Scrooge helping Barko, whose rheumatism was threatened by the rolling hills. Slick then dropped off drugged fishes to knock out Scrooge's team. Scrooge discovered this, but then succumbed the fumes of the drugged fish himself. Barko was the only one unaffected, and bravely pulled the sled by himself, along with the Kyoodles and Scrooge aboard.
Later that night, Scrooge awoke to see that his sled dog buddy had pulled the whole way. Scrooge then volunteered to pull while Barko slept on the sled the rest of the way. The team then caught up with Slick's team by the Frozenjaw River's icy shore. Slick saw Scrooge, then fired his pistol sending the old duck quadzillionaire into the icy waters. Barko rescued his friend just in time. As the sled crashed through the ice, Barko was pulled under just as Scrooge made it near where his receipt laid at the mercy of Soapy Slick. Scrooge then did the unexpected, and saved Barko instead of his fortune. Upon the cracks of ice, Scrooge and Barko ("It's all right, old fellow! We sort of belong on this ice cake together!"). All seemed lost until Huey, Dewey, and Louie showed up with Poly Poly, a polar bear cub raised by the Arctic Patrol of the Junior Woodchucks. Poly Poly rescued the two friends, and just as Slick got the receipt, news reporters, courtesy of Donald Duck, arrived before he could rip it.
In the end, Scrooge got to keep his great fortune, while Barko and Poly Poly became famous animal heroes. Once again, Barko's potential was recognized thanks to Scrooge, and he reclaimed his title as the Champion of the North.