Two powerful German cannons control the seas past the Greek island of Navarone making the evacuation of endangered British troops on a neighboring island impossible. Air attack is useless so a team of six Allied and Greek soldiers is put ashore to meet up with partisans to try and dynamite the guns. Maj. Roy Franklin is the officer assigned by the British to lead a task force to put the guns out of commission. When Franklin is injured, the mission winds up in the relatively inexperienced hands of Capt. Keith Mallory who does not get along too well with explosives expert Cpl. Miller and Greek patriot Andrea Stavros, especially when it becomes known that there is a traitor in their midst. Resistance leader Maria Pappadimos identifies and kills the traitor, but their mission is not yet completed.