Rainford was on a boat. It was dark and and raining and he was walking around the boat and he fell off of the boat.No one new that he had fell off the boat so they left him in the water.
Rainsford and general Zaroff are fighting for different goals. Zaroff for fun and amusement and Rainsford for survival and escape.
Rainsford is curious about zaroff and his magnificent mansion but he is repulsed when he finds Zaroff now. prefers hunting humans not animals because he said that he needs a harder target. Even worse Rainsford discovers that he is to be the prey for Zaroff next hunt.