What is The exposition for three skeleton key?

Three Skeleton Key is about these three men who work in a lighthouse there names were Le Gleo, the narrator, and Ichoua. They were on a small island off of Guiana called Three Skeleton Key.

Itchoua sees a ship and alarmed them. The ship was abandoned and crashes into the rocks. They found out it was rats on the ship and they covered the island and blanket the island so they go trapped on the island. The rats ate through the window cover and Le Gleo, narrator, and Ichoua got trapped in the upper level.

They figured out if they don't light the lighthouse so someone can notice something is wrong. The coast rescuers failed the rescue attemps and the meat boat came and the rats left off the island. The rats got burned and eaten by sharks because they set the meat boat on fire. The men survived and the narrator to three skeleton keys.