The writer has highlighted a universal theme in this story. It is that we can arouse the goodness in the life of a man by love, understanding, sympathy, and respect. Once upon a time there was a man who went around selling self-made small rattraps of wire. His condition was too miserable to beg and do petty thefts. He was in rags, with sunken cheeks and hungry eyes.

One day an ideal flashed into his mind. He thought that the whole world around him was a big rattrap. It offered riches, joys, food, shelter and clothing like a bait offering cheese and pork in a rattrap for the rats. Those who were tempted to touch the bait, it closed on them bringing an end to everything.

One dark evening while staying at a crofter's cottage, he was given food and lodging. But the next morning the tramp stole his thirty kronor. He kept on walking all day long on the same path in the forest. On hearing the sound of hammer strokes, he reached the ironmill and lay near the furnace.

The ironmaster mistook him to be his old acquaintance and invited him for Christmas cheer but he refused. He sent his daughter Edla who persuaded him to their house. After having him well dressed, the ironmaster found that he mistook him Captain “Nils Olof.” So he ordered him to get out at once. The young girl interceded for him and said she wanted him to stay as they promised him Christmas cheer. He was treated like a real captain with food. In their absence when they were at church he left. At the Church they learnt the rattrap seller had robbed the old crofter. So they became worried.

When they returned the valet told that the stranger had taken nothing with him and left behind a Christmas gift for Miss Willmansson. She found a small rattrap thirty kroner and a letter in it. The letter stated that she had took him as if he were a captain, so he would be nice to her as a captain. It had given him power to cleanse himself.