UPDATED 18 May 2014 - the book, formerly known as In Apple Blossom Time is now out in paperback and has been renamed Time Bomber.
At first glance I am the last person to be part of the target audience of Time Bomber by Robert Wack, set in 1944. I hate war films (or rather I have never seen one and never particularly want to). I even avoided War Horse because of the setting. As for written material, the last time I read anything set in the Second World War it was a comic back in the 1960s (usually, as I remember it, involving daring raids to blow up a submarine pen) when there was still a considerable appetite for gung-ho WW2 stories. But this is different.
I'll admit it appealed to my vanity that the author claimed to be inspired my book How to Build a Time Machine to create a novel around the extraordinary war career and death of Dutch-American mathematician Willem van Stockum, one of the first to take on the implications of Einstein's work on general relativity that implied the possibility of using warps in spacetime to create closed time-like loops that should enable travel backwards in time.
I can't deny I found the book gripping. I expected to read bits of it as and when I had a bit of time between research reading for my next book, but in practice once I started, Time Bomber took over and wouldn't let me put it down. If you are going to be picky, some of the dialogue is a little stilted and there are too many pages given to introspective thought, but the wartime scenes, both van Stockum's experience as a bomber pilot and the scenes on the ground in Normandy in 1944, are well-crafted and place the reader uncomfortably deeply into the action.
The book would have been quite interesting if that were all there were to it, but it is lifted to a new level by the inclusion of mysterious figures, some who appear to be trying to save van Stockum from his 1944 death, and others to prevent this interference. Van Stockum's impact on the physics of time travel would, it seems, have repercussions in the future, if he can continue his work after the war.
Technically there is a flaw in the approach taken to time travel here, as no device reliant on general relativity to travel backwards in time could reach further back than when the machine was first created, but I am always sympathetic to the argument that in science fiction the most important word is 'fiction' and it while every effort should be made to stick to known physics, if necessary the detail has to give way to making the story work. Apart from the violation of what I think of as the 'cardboard box of time effect' (more on that another time) the author does pretty well at keeping the science on track.
It won't appeal to everyone (and if you find the first couple of chapters confusing, bear with it), but I recommend giving Time Bomber a go. It is available from Amazon.co.uk and Amazon.com.