The Ultimate Vampire Resource and Directory

Upon hearing of several recent robberies of food delivery trucks in Mexico, Joyce Manning, the sister of Army officer Lt. Col. Glenn Manning, becomes convinced that her brother survived his fall from the Hoover Dam at the end of the first film. Along with Army officer Major Mark Baird and scientist Dr. Carmichael, she goes to Mexico to look for him.

It is discovered that Manning, now grown to 60 feet tall after being exposed to plutonium radiation, survived his fall from the Hoover Dam at the end of the previous movie, but he has gone insane and part of his face was left disfigured following his confrontation with the Army at the dam. Manning is captured and drugged by the Army and taken back to America, but he again escapes and goes on a rampage through Los Angeles and Hollywood. Eventually Joyce makes him snap to his senses and realizing what he has done, Manning kills himself by electrocution (somehow causing the movie to change from black and white to color for the final minute) on high-voltage power lines around the Griffith Park Observatory.The ending, involving electrocution, is almost exactly like the death of 50-ft Woman.