The anger and frustration and confusion and pain of a dying man, surrounded by people who have little or no concern for him at all. His entire life has boiled down to a few friends who are nothing more than coworkers interested in his position, and a family that does not love him but thinks of him as a burden. That's this book in a nutshell. It's famous as one of Leo Tolstoy's great achievements, a mastery of the mind.
Depending on which version you have, his name might be Ilych or Ilyich or even Ilyitch. The first chapter is interesting, the next few chapters are pretty dull. Then you find yourself drawn back in as Ivan Ilych slowly becomes aware of his illness, is then stymied by it, then the slow downfall as it controls him, and then as it ultimately consumes him.