Thunder in the Sky — Elizabeth Peters

It is 1914 and Amelia Peabody and her husband Emerson are back in Egypt for another season of archaeological excavation. But this year a new menace hangs over the dig: rumblings of war abound in Europe while over in the East, Turkish and German forces are massing for an attack on the Suez Canal.There are problems closer to home too: their son Rameses, passionately opposed to the war, is collecting white feathers and challenges from the British community of Cairo, their beautiful ward Nefret seems to have become involved with Amelia's detested nephew Percy, while David, the young Egyptian married to their niece Lia, has been interned because of his nationalist sympathies. Even Amelia finds it difficult to concentrate on pyramids when her children are in trouble and Cairo teems with enemy agents, including her old nemesis. Can Amelia unmask the Master Criminal and prevent a bloody uprising in Cairo, rescue Nefret from the attentions of her nephew, defend her son against unknown enemies and prevent Emerson from dashing off to fight in the looming war? If anyone can it's Amelia - but this time she is going to need all the help that she can get; and some of it from a completely unexpected source.