At the end of the 19th century, a young man named Ephraim goes to a remote island to take the post of an assistant lighthouse keeper. The guy has to spend a whole month in company with a lame and very suspicious old man Thomas. The lighthouse keeper considers the newcomer to be his subordinate and does not allow him to practice managing the lighthouse. Soon Ephraim understands that something is changing inside him, gradually the guy ceases to recognize himself.