Wartime tale of a group of British scientists efforts to develop the first radar system. They did it just in time for it to be used in the Battle of Britain against the might of the Nazi Luftwaffe. Without it the little island could well have been overrun.

Determined, independent Bridie Quilty comes of age in 1944 Ireland thinking all Englishmen are devils. Her desire to join the IRA meets no encouragement, but a German spy finds her easy to recruit. We next find her working in a pub near a British military prison, using her sex appeal in the service of the enemy. But chance puts a really vital secret into her hands, leading to a chase involving Bridie, a British officer who's fallen for her, a German agent unknown to them both, and the police...paralleled by Bridie's own internal conflicts.