Mercedes is supporting antagonists during Chapter 5. She is spoiled and sellfish woman, also sister of Hal and wife of the Charles. She is only a female who appears in a book, not counting Alice and Molly Miller who were only mentioned.
Mercedes' inexperience is shown, when she can't pack sleds and can order Hal and Charles to unpack sleds, because she forgets some things or things look bad on sleds. One of the older mushers starts to say that it's better to get rid of tent, because it is spring. But Mercedes doesn't want to get rid of the tent. When Buck and other dogs are ordered to mush, they can't pull sleds and Hal starts to beat the dogs, but Mercedes asks him to stop. Hal doesn't listen to her, and says that dogs are lazy. One of the experienced mushers start to say that dogs need rest. But Mercedes defeat her brother and agrees with him, that dogs need to beat. But dogs still can't pull sleds, Mercedes hug Buck and asks him to pull. One of other mushers, say that runners are frozen in snow, and when runners are broken dogs start to run as crazy and all of things on sled is droped on the ground. Dogs are stopped by other people, who say to trio that they need to get ride of some things (like tent, or unwashed dishes). When Hal and Charles start drop Mercedes clothes and other articles on the ground, Mercedes starts to cry and starts to clasp hands about knees, rocking back and forth broken-heartedly. Later she buys with Hal and Charles 7 news dogs.
When the trip starts, Mercedes starts to steal food and give it to dogs, what was bad thing, because they only travalled 1/4 of the way and food run out. And when Hal or Charles start fight who have done more job, Mercedes tried to stand tothe side with Hal, sometimes with Charles or with both. But she is neautral in they fights. When dogs started to die of starvation, Mercedes doesn't want to walk all the way and she insisted on to ride on sleds. Hal and Charles don't want that she rode on sled and once they droped her on snow, but she doesn't move. And after travelling 3 miles, Hal and Charles returned back and put her on sled. Mercedes continued ride on sled, but because of her weight more dogs started die and die.
Mercedes with her husband and brother got to John Thorton camp, John Thornton say that they don't need to go on ice, because ice can break, Hal doesn't listen to Thornton and insisted dogs to move. Mercedes watchs how Hal starts beat Buck, but she says nothing and when she saw how John Thornton hit Hal, she starts to scream, cry and show hysteria. Soon she sees how Buck is taken by Thorton. Mercedes, with her brother and husband, and other dogs start go on ice, but ice breaks and Mercedes with others sank in the lake, John Thorton and Buck see everything.