This book is significant as being the only non-science fiction fiction book that Arthur C. Clarke ever wrote. It was inspired by (and partially, I'm sure) based upon his experience in World War II as a member of the Royal Air Force, using the GCD (Ground Controlled Descent) system to "talk-down" pilots. This is the setting of the story. Though the technology described is not impressive by today's standards (almost 40 years after the book was written, and 60 after the events it fictionalizes), the radar system is gone into in a quite detailed way, and it's obvious that Clarke knows what he's talking about. However, aside from this, there is another reason that this book is significant. Here we actually have Clarke employing a main character (Alan Bishop) as a main character, and developing him. Perhaps this was spurned on by his own personal involvement with the setting of the story, but, whatever the reason for it, this is probably actually the most "human" story that Clarke has ever put out. Those who claim that they can't read Clarke because all of his stories are just complex scientific esoteria that nobody understands wrapped up in a science fiction premise with cardboard cutout carichatures of characters who act merely as set pieces must revise, at least partially, this view of the author after reading this book. We see Clarke develop the character of Bishop. This, indeed, is one of his relatively few books (including among them Imperial Earth, The Songs of Distant Earth, and perhaps The Fountains of Paradise), where a human being is actually the star of the show, and not a machine or an idea. This is a bit of a change of pace for the reader of ACC's fiction, and it is a pleasant diversion. While this is most assuredly not one of his major works, it is an enjoyable read, and an interesting contrast. It balances the technological and human elements of the story rather well. A nice, quick read as well. Pick it up if you can find it.