Dark City (1998)

The whole city is actually a conserved environment in space. The aliens control the city and are hoping to use the humans to save their dying race. John (Rufus Sewell) learns the aliens powers with the help of Kiefer Sutherland and uses them to defeat Mr Book. He remakes the city and lets the sun shine down, then makes a beach and ocean. He tells Mr Hand that what makes us human isn't in our heads, and they were looking in the wrong place. He meets Jennifer Connelly on the pier and they both walk to the beach. She has no memory of who he is.

Gary Dorston