Zero Trust is transforming enterprise security — and this audiobook gives you the practitioner's guide to implementing it in the real world. Whether you are a CISO building the business case, an architect designing the implementation, or an engineer deploying the controls, this guide takes you from first principles through enterprise-scale deployment. You will learn why the castle-and-moat perimeter model has fundamentally failed — and why that failure is accelerating as cloud, remote work, AI agents, and machine-speed attacks dissolve every assumption perimeter security was built on. You will understand the five pillars of Zero Trust (Identity, Devices, Networks, Applications, and Data) and how they combine into a cohesive architecture that does not depend on network location for trust decisions. The audiobook covers why identity is the new perimeter and why phishing-resistant FIDO2 authentication is now essential, not optional. You will learn how to replace VPN with Zero Trust Network Access, how to protect private applications without exposing them to the internet, and how to extend micro-segmentation from the data center to cloud workloads, serverless functions, and AI agents. A dedicated chapter covers Zero Trust for Operational Technology — the unique challenge of securing industrial control systems, SCADA environments, and railway signaling systems that run for decades on protocols that were never designed with security in mind. The Estonian Railways case study walks through exactly what worked, what broke, and what the team learned. You will learn how AI agents create a fundamentally new security principal — one that acts at machine speed, may orchestrate thousands of sub-agents, and requires a completely different approach to identity, permissions, and audit logging. Task-Based Access Control, cryptographic workload identity, and behavioral anomaly detection for agents are covered in depth. The implementation roadmap covers a realistic five-phase, 36-month journey from legacy perimeter to full Zero Trust — including the change management reality that technology is only 30 percent of the work. Real-world case studies from a 20,000-user enterprise across 8 business units, Estonian Railways, Suffolk County New York government, and Just Eat Takeaway provide concrete grounding in what enterprise Zero Trust actually looks like in practice. Not affiliated with or endorsed by any technology vendor, cloud provider, or certification body.