I skipped a few Horus Heresy books because I wanted to read about the Thunder Warriors and The Outcast Dead was the recommended source. The main story relates to a powerful astropath who, after surviving a warp accident on a spaceship, got almost mad and apparently incapable of performing his duties, and who by chance will party with some renegade Space Marines who were imprisoned on Terra, so not much about Thunder Warriors there... it is true that part of the later plot does involve them (I don't want to spoil anything), but I was hoping to know more details.
Still the main story is quite interesting, at first unfolds slowly but then takes pace and I read the last third of the book way faster, devouring the words and trying to learn what happened next. Another good Horus Heresy novella, and one that goes quite deep into astropaths, cryptopaths, navigators and related psykers.