A nerdy high school super whiz experiments with a chemical which will transform his guinea pig "Mr. Mumps" from a gentle pet into a ravenous monster. In a fit of rage against his tormentors at the high school, Vernon Potts goes on a killing spree, eliminating all of those who ever picked on him - the Gym Coach, the School Jock, The Creepy Janitor & his hated teacher, Ms. Grindstaff.
A mentally unbalanced man is obsessed with the idea that a black cat is possessed. He tortures and kills it. Later, he comes to believe that the cat has returned from the dead to kill him.
During WWI, the Germans try to encourages and hires a band of certain Mexican guerrillas and bandits to make trouble on the Texas border and attack the Stonewall Farm. He plans this so the Americans will have no choice but to send more troops to Texas instead of Europe. Masterminding the plot is a German spy who has, at his disposal, the RX4, a specially equipped weapon-bearing automobile of awesome speed, but a U.S. Army lieutenant carries the day with his own fleet of Model T racers.
