Books set in a dystopian past/future like 1984 or Fahrenheit 451

Recently finished 1984 and I've just started Fahrenheit 451 and I'm loving it. I'm looking for a book where its set in a dystopian period, and the characters are having to sneak around for whatever reason (government, evil organisation, general public opinion of ehat they are doing is wrong etc) I don't really know what to search to find books like this 'psychological ' and 'thriller' tend to give me horror esque type books and that's not what I'm looking for right now even though I enjoy reading those too. Thanks for any book or author recommendations!