"All of Guilfoile's characters, whether clones, online 'avatars' or killers, inhabit the real world. Their motives are small and familiar, and they can't see past the ends of their own noses. When the book's secret is revealed, it's not about the violence in computer games, or about nature versus nurture, or the overreach of science, or the Pandora's box of cloning. It's about human failure, the power of conviction and the random disorder of daily life. Ultimately, Guilfoile's finely rendered re-creation of the real world is what elevates Cast of Shadows."
——Mark Schone, New York Times
"An altogether satisfying thriller...while technology permeates Cast of Shadows, it is the all-too-human vulnerabilites of characters we come to care about that brings fear to the tipping point."
——Sherryl Connelly, The New York Daily News
"Besides serving as a cautionary tale against the consequences of cloning, this terrific book accomplished something else: It made me reconsider my opinion about mysteries set in the future."
——Leslie McGill, Kansas City Star