You are a team of federal marshals, who turned out to be so called "Shutter Island".
Here is a psychiatric hospital for the mentally ill criminals.
All anything, but on the island already every day it is raining and the power supply is disrupted.
Before the backup power runs out, no more than 75 minutes are left, and only electricity is holding back the crazies in the cells.
You need to restore the power supply of the lighthouse and get out, but the only way out of the island is through the pier.