The spectre of another world war haunts journalist Walter Craig and disturbs the peace of his seaside holiday. But below the Cornish cliffs, hidden by churning seas, the enemy is very real indeed, and much closer than anyone could suspect. Craig and his singularly resourceful fisherman friend alone discover the terrible truth - a potentially devastating threat to Britain's merchant ships - and alone must risk their lives against the might of the German navy. This is a classic wartime adventure from the master of suspenseful storytelling.