When he must detour while en route to Egypt, Royal Air Force pilot and reconnaissance photographer Peter Ross (Alec Guinness) finds himself at the center of the Axis' infamous Siege of Malta in the Mediterranean theater of World War II. Aided by the beautiful Maltese volunteer Maria (Muriel Pavlow), Ross battles against the odds to obtain recon on the Nazi squadrons in the area and help defend the people of the small but critical island nation.