Bog Child by Siobhan Dowd

Digging for peat in the mountain with his Uncle Tally, Fergus finds the body of a child, and it looks like she's been murdered. As Fergus tries to make sense of the mad world around him - his brother on hunger-strike in prison, his growing feelings for Cora, his parents arguing over the Troubles, and him in it up to the neck, blackmailed into acting as courier to God knows what, a little voice comes to him in his dreams, and the mystery of the bog child unfurls. 
Bog Child is an astonishing novel exploring the sacrifices made in the name of peace, and the unflinching strength of the human spirit. From Goodreads.

I was annoyed during the first two parts of this book - really liking Fergus but worrying about the trouble he was in for couriering packets across the border. But I love the twists in the third part that I had just not seen coming. That changed the book from an okay read to a really good read. It was also a very interesting story about the bog child that came bit by bit through the whole book.