In Gary Richmond, a zookeeper at the Los Angeles Zoo, remembers the strict instructions he was given when he received the master keys to all the animals' cages. His supervisor made it very clear that constant vigilance was necessary for ensuring the safety of the animals and all the people at the zoo. Gary's greatest responsibility would be to guard his keys and to make sure he used them wisely - only opening or closing those doors that absolutely had to be opened or closed.

For the first few months, Gary was the model of vigilance. But one day, Gary was tending to the polar bear when he realized he had made a horrific mistake. The massive polar bear, easily the size of three large men, was the most dangerous animal at the zoo. He hated humans and had tried to maul anyone who passed his c…