The secret squadron commander and his agents are having plenty of excitement in the upland valley in Yugoslavia, where they and their guerilla friends have been trapped by the Nazi forces under the command of General von Lutz. At three o'clock, just as Captain Midnight, Joyce, Chuck Ramsay and the young guerilla chief rush to the entrance of the hidden airfield's underground hangar, they saw a large number of swastika marked transport planes from which paratroops were plunging towards the runways below.