The report of findings of the Columbia Accident Investigation Board is an excellent read. The level of detail is remarkable and it is a real page turner. Its available as a free pdf, but NASA have split it up into a number of volumes now.
The report really lays into the power structure at Nasa, the way that Marshall and Johnson were at odds with each other, budgetary issues that placed pressure on management to accelerate schedule and cut corners, the reliance by NASA on United Launch Alliance to self-inspect etc, etc. Most sobering is the retelling of the desperate attempts by reliability ebgineers to get orbital imagery but being turned away because they didn’t use “proper channels”.