Kidneyfoot Cassidy is a homeless beggar. He needs a coat. He's out in the cold without one, after someone took his off of him well he was sleeping. Now he says he'll get himself a coat -- by taking one from someone else. So, he kills a man and puts on the dead man's coat.
The dead man's coat is the warmest coat Cassidy has ever had. He feels no remorse about how he got it -- he has no conscience. He has some plans for making sure he isn't prosecuted for the crime. He tries to avoid being noticed. At one point he remembers an old saying he heard as a kid: "Wear the dead man's coat, none of take note."
You can put on the dead man's coat, yes. That's easy enough. Can you take it off again, though? Some better advice: Don't wear the dead man's coat. If you do, you'll regret it.