It starts out with him winning a match and coming home to his wife and kids in a nice home. Then he breaks his hand and badly loses a match and loses his license. It's the depression and he can barely get more work. Their electricity is cut off, they live in a rough basement, and he went to the government office to get welfare, which wasn't enough, and then asked the boxing guys he knew for money. He got $5 more than he needed.
His hand heals during this time and he becomes stronger working on the docks every other day or so. His director comes and says he's got a one-time match for Jim, and the prize is $250. Jim took it and finished even with the other guy and got $123 of the prize. He was good enough that his director got his license back and he wins match after match. Then he's asked to fight a man who has killed two people in the ring. His wife tries to keep him from going, but he says he must.
The kids are at the aunt's and listen, hidden, to the radio. His friends from the docks listen to a bar radio, and a church is full listening to the radio. He's become an inspiration for the lower classes in the middle of the depression. He wins the bout and continues to box for a while more.
He was in WWII and then worked at the docks with his own equipment.