Adam Knight is a young man who, having tried several jobs, decides to set up an agency, 'Knight Errant '59', to solve other people's problems - whatever they may be. There's plenty of scope and, assisted by former reporter Liz and idealistic young writer Peter, the latter-day Sir Lancelot is kept busy with a variety of curious and exciting cases.

The series had two titles, Knight Errant '59 and Knight Errant Limited of which only two episodes exist out of the 75 produced.