Never Trust, Always Verify is a practical account of Zero Trust after the perimeter stopped being a wall. It walks one firm from the castle it already built, lists, firewalls, proxies, tunnels, and the box that could read the application, to a door that can refuse this request and still allow the next one. The running example is a lawyer, a matter file, and a second app that must stay open when the first permission dies. A plant, a clinic, and an agent take the same test. The book is for the people who have to make that door refuse on a Friday: architects, operators, identity, network, the inspect plane, and the desk that will be handed a page and told it was containment. It is not a vendor briefing and not a maturity dashboard. A group is not a person. A path is not a credential. A publication is not a door.