As soon as Rainsford discover that he is going to be hunted at night by General Zaroff and that confreontation and a battle to death is inevitable the rising actions stars.
The rising action of a story begins when a conflict is introduced. A story's rising action includes the major plot points leading up to the climax. A conflict is defined as any kind of struggle between two forces. These forces can be anything from two human beings to a human being against an inhuman force. In this case, since Rainsford has fallen into the water, there is now a person versus nature conflict which starts the rising action.
