Seventy-five years on from the attack on Pearl Harbour, questions remain about how the world's most powerful nation was caught by surprise. This Secret History documentary reveals new insight into what Washington knew before the attack, and whether Churchill and Roosevelt conspired to allow it to happen. Within the space of two hours, the devastating assault by Japanese forces left nearly 2500 people dead and 19 ships destroyed or damaged. An investigation ordered by President Roosevelt found Admiral Husband Kimmel, Commander in Chief of the Pacific Fleet, guilty of dereliction of duty. With his career in ruins, Kimmel became a broken man. But was he really to blame? Now, new research reveals what Washington knew prior to the attack and uncovers a crucial dossier that could have prevented it.