Sr. Bertrille asks Sr. Olaf, an aged nun, what she wants for Christmas. Sr. Olaf, a native of Norway, replies A White Christmas. Sr. Jacqueline and Sr. Sixto are stunned when Sr. Bertrille asks their help to make it snow for Sr. Olaf. At the Weather Bureau, Sr. Bertrille learns of experiments in seeding clouds with pellets of dry ice. The three nuns fill wheelbarrows full of dry ice at Carlos Ramirez' discotheque. Sr. Bertrille takes to the air to seed the clouds and soon snow is falling on the convent. When trade winds carry her over San Juan, snow starts to fall and the tourists head for home. Mother Superior remarks it won't be a very Merry Christmas in San Juan. Carlos learns that Sr. Bertrille is responsible and scolds her. She suggests that Carlos collect money from his friends for the little people. Carlos collects $5000 and Sr. Bertrille goes aloft to drop bills instead of snow. The tourists decide to stay and wire everyone to come to San Juan. Knowing the businessmen will never believe the true story, Carlos goes broke in paying them off. When Sr. Olaf, who hasn't been downstairs in months, comes to the Christmas party, Sr. Bertrille thanks her for the nicest Christmas she ever had.