Movies
We'd better get back, 'cause it'll be dark soon, and they mostly come at night...mostly.
— Newt · Aliens
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker urges a return before darkness because the unnamed others usually come at night. Repeating 'mostly' qualifies the warning in an unsettling way. Night is presented as the main danger, while the qualification leaves room for an exception to that pattern.
Context reviewed