Wool stories are getting longer and remain fantastic. By part 4, sh*t is getting real and the story is getting grittier. The action picks up as we get to witness the uprising in the silo and see the comfortable but stifling order and safety unravel. We finally get to see what lies beyond the hills that used to make the boundary of the visible world for the silo inhabitants. The characters remain well-written and easy to care about. I still love Juliette, she is a kickass heroine who remains believable, practical and likeable. We also get to know a few more people in the silo who are well-developed even in the short time they are on-page. The only character I have a problem with is Lukas; I just don't see why Juliette would be attracted to him. Hopefully he will get better in volume 5; I am sure more character development for him is coming.Great read overall. Moving on to Wool 5 immediately.