Imagine how this tale of a Nazi invasion of England struck readers in 1940: Intrepid British agents infiltrate native born fifth columnists preparing the Germany invasion. Now put yourself in the place of English readers who suffer from Nazi bomb attacks, which are part of the plot!
The story is a preposterous, really, but to say why would be to spoil it. If you can accept such an elaborate conspiracy and just go with it, then the story is sensationally and marvelously told after the first 30 pages. This is the fourth book of a series, and John Creasey, originally writing under the name Norman Dean, does not bother to fill us in on who all these people are and why they do the things they do. It becomes clearer after the fourth chapter and eventually clear, but I nearly gave up before that point. Stick with this book for what they call a rattling good yarn.