Between 1941 and 1945, merchant ships escorted by vessels from the US, Canadian and British navies delivered 4 million tons of essential goods to the Soviet Union. In this documentary, Jeremy Clarkson retraces the journey of the convoy of 35 ships codenamed PQ17 from Iceland to the Russian port of Arkhangelsk in June and July 1942, revealing how the Anglo-American mission became one of the biggest naval disasters of the 20th century. Featuring testimony from men who served on the vessels.