I was only able to skim-read this, I'm afraid, as the writing is (to my mind) so appallingly bad. Overwritten, self-consciously 'literary', try-hard rubbish. Having skim-read it this morning, I must say there was very little else I liked about this. The character POV is unstable (e.g. a chapter written from Frankie's POV will suddenly flip to the inner thoughts of a random man who only appears for half a page), the characters are underdeveloped and their relationships unconvincing, and the whole thing is too pat (Frankie meeting Will in the shelter, Harry having a coronary just as the entirely unlikely U boat surfaces etc.).
What did work were the scenes detailing the uncertainty and fear of the refugees trying to get away - I choked up a few times during this section, and this is in spite of the poor prose, so clearly a powerful subject. But ultimately it seemed quite offensive to use the story of these countless deaths and separations as the backdrop to a story about one person's pain being temporarily spared. I feel like, if Frankie had seen all that she had seen and been through all that stuff, she would have got home feeling like 'who gives a fuck about one single person's loss?' But that's probably just me 
Anyway, sorry not to be down with this one. Also sorry if none of the above makes sense; my children haven't yet grasped the concept of giving mummy some peace and quiet to collect her thoughts.