Hitler's plan to loot a treasure-laden island off Greece is underway. A prison camp is built where inmates dig up priceless art under the eye of the Austrian commandant Major Otto Hecht (Roger Moore).
Zeno (Telly Savalas), the island's resistance leader and Eleana (Claudia Cardinale) scheme to defeat the occupiers. Leading a group of freedom fighters, they clash with the Nazis as they try to save the lives of condemned prisoners and to save the treasure hidden in the mountaintop monastery.