Dick Marlow, a British agent, has parachuted into the occupied Netherlands to retrieve vital documents. Whilst on the trail of the papers, he poses occasionally as an American journalist and a Gestapo officer. He meets and falls in love with a Dutch woman who professes solidarity with the British, but matters become complicated and dangerous when it transpires that the woman's brother is in possession of the documents Dick Marlow needs, and is far less kindly disposed towards the British than his sister – or is she?