Carruthers finally puts the riddle together. The Germans are linking the canals and the railways, dredging passages through the shifting sands and hiding a fleet of tugs and barges. The only explanation is that they are going to secretly transport a powerful German army across the North Sea to invade Britain's east coast. He escapes after grounding the tugboat and rushes back to Davies. He finds him and explains how they must flee before the Germans come after them. They convince Dollmann and Clara to come with them to avoid Dollmann's being arrested by the Germans, who will think he has changed sides again. They promise Dollman immunity from being charged for treason in Britain - which, acting on their own and not having any authorization from the British government, they were not truly in a position to promise. As they sail across the North Sea, Dollmann commits suicide by jumping overboard, presumably to avoid disgrace and probable arrest.