An English man mapping sandbanks off the German coast get his friend to help investigate a German plot to invade England. Much of the film takes place onboard the the British and the German ships giving a claustrophobic feel at times as the two sides play cat and mouse with eachother trying to find out what the other side knows. Jenny Agutter is caught up in the intrigue being the daughter of one of the Germans but falling for Michael York.
3/5 
Michael York
Jenny Agutter