Raskolnikov heard about a pawnbroker's news. This pawnbroker was an old woman who was greedy and harsh to people who borrowed money. Raskolnikov believed that killing this old woman and taking her money could help many poor people.
He repeatedly thought about this idea and felt it was the right thing to do. He believed that great figures like Napoleon could also kill for higher goals.
Although this idea made him afraid, he couldn't suppress this impulse. He began to prepare to carry out this plan.