On the night of 16 September 1961, UN Secretary-General Dag Hammarskjöld's plane crashed under suspicious circumstances in the British colony of Northern Rhodesia. The Swedish Hammarskjöld argued for the independence of Congo and had thus made itself unpopular with the colonial Western powers. The crash sparked one of the most mysterious murder plots in recent memory. More than 50 years later, the Danish filmmaker, journalist and provocateur Mads Brügger sets out to uncover the truth of this cold case once and for all.