The Quantum Thief, written by Hannu Rajaniemi, is a science fiction novel that explores the concept of quantum reality in a future where technology and virtual reality are seamlessly integrated into everyday life. The story follows Jean le Flambeur, a master thief who is captured and forced to participate in a high-stakes heist. As Jean navigates the virtual realms and quantum realities, he questions the nature of identity, memory, and the boundaries of existence.