I stayed up way too late because I just couldn't put this down. The tragic story of a woman with 5 young children who, by way of her death from a particularly vicious cancer, should help save the lives of probably almost every one of us, is positively fascinating. I also like the author's style as she weaves the stories of the past and the present, along with updates on the people we've met in the book and an afterword discussing the moral and legal implications of the issues in the book, and they make a very satisfying read. 

Question: How is the truth?
Answer: The tragic story