Factoring humanity - Robert J Sawyer

From the author of ILLEGAL ALIEN and FRAMESHIFT, more entertaining, thought-provoking, thoroughly modern SF. We gain access to the fourth dimension by deciphering an alien message and discover there the Overmind that links us all. Heather Davis, a psychologist, deciphers the alien message. She lives alone since her younger daughter, Rebecca, recently moved out. Her eldest child, Mary, killed herself a year ago. After that, she and her husband Kyle Graves, a researcher working on quantum computing, separated because neither of them could handle the grief, but they do not plan to stay apart forever. But they are driven further apart by Rebecca's sudden, astonishing accusation of child sexual abuse against her father, with the further unspoken but crystal clear accusation that he abused Mary as a child also and that Mary killed herself because of it. Though Heather tries not to, she gives the idea credence...When she breaks through to the fourth dimension and the Overmind, she is able to prove first to herself and then to her daughter Becky that Kyle is completely innocent: Becky, and Mary before her, are victims of the same psychologist, an abuse victim herself, who has planted false;Thus the Overmind abolishes subjectivity and related error at a stroke. History moves beyond debate and falsehood. And even before Heather goes public with her discovery (after sharing it with her family), a wave of empathy washes through the world as the alien Overmind at last makes contact.