As it's the second book in a series of four, I wouldn't recommend reading The Edge of the Cloud on its own, but it stands out as my favourite. The story of Christina, Will, and aeroplanes is a wonderful tale of why women love single minded men who ignore basic feminine needs (like when he gets his friend to tell her he's gone to Switzerland instead of telling her in person). He flies her over the channel and crash lands the plane, lets her stay up all night helping him fix the plane, and never changes out of his oily overalls. Yet she loves him because he's exciting, forward thinking, brainy (unlike his dumb brother), listens to jazz, and faithful. The beautifully evocative language gives their romance a tenderness missing from my description, while the heavy threat of the first world war is ever present, so there's a terrible poignancy hanging over all the joyous times, knowing things will never be the same again for Christina and Will, and the other fun loving characters.