One of the best of dozens of British books about secret raids against the Germans. Two years before D-Day, Sgt. Jack Nissenthal, a Jew and a Canadian in the R.A.F., is sent on a special mission during the Dieppe assault (Green Beach) -- to discover the extent of German radar refinements. The British have developed a magnetron -- this gives their own radar extremely fine focus: do the Germans have it too? In a small concrete shelter near Dieppe sits a well-guarded shack which Jack's squad is to invade and dismantle. Aside from his being a Jew, Jack is too valuable a technician to be allowed to fall into German hands and he is told that his squad has orders to kill him in the event of capture. He also is given a cyanide pill to carry. The battle is described with stinging detail as his mates die about him. Though they fail to penetrate the radar shack (not enough supporting fire), they cut all lines leading into it and when the Germans switch to radiotelephone, the Allies know that their magnetron is still top secret. This rehearsal for D-Day is said to have changed the course of WW II. The story is told with clenched immediacy and much blood.