Erskine Childers · 1903 · sea

Erskine Childers's 1903 novel, the first modern spy story. A bored Foreign Office clerk accepts a vague invitation to go duck-shooting in the Baltic and finds his friend living aboard a small converted lifeboat with a chart obsession and a suspicion. Working the tidal sands behind the Frisian Islands, the two of them find what the Germans are building there.

1. 1
   Flensburg

   Carruthers arrives in the Baltic expecting a yacht and finds the Dulcibella, small and entirely unsuitable - and Davies, who has not mentioned being led onto a sandbank on purpose by a German pilot boat.

2. 2
   The Kiel Canal

   They take the canal through to the North Sea, and Davies lays out his case over the charts - that the man who tried to drown him works for the German government, and the sands are worth killing over.

3. 3
   Norderney

   Among the Frisian Islands they sound the channels behind the sands at low water in fog and autumn gales - navigation that fills the book with tide tables, and the only way to learn what is happening there.

4. 4
   Memmert

   At Memmert a salvage company is doing work no salvage company would do, and Carruthers gets close enough in the dark to hear a meeting - and to grasp that the sands are being surveyed as a launching place.

5. 5
   Emden

   The answer is an invasion rehearsal - shallow-draught lighters towed from the Frisian channels to England, using exactly the water the Royal Navy cannot enter - and two amateurs must get the proof home.