What great shock greets Louise in the last paragraphs of The Story of an Hour by Kate Chopin?

Louise was shocked to death when her husband appeared in the front door of their home.

Some one was opening the front door with a latchkey. It was Brently Mallard who entered, a little travel-stained, composedly carrying his grip-sack and umbrella. He had been far from the scene of the accident, and did not even know there had been one.