I would ignore dpg, he fairly repetitively asks the same questions, and expects the whole plot of a movie to condense down to under 50 words.
The point of a logline is to hook the reader, you hook a reader by getting them to ask questions, which means being more vague rather than more specific. If I can get the whole movie from 50 words or less, why would I go see the movie?
Not every movie has to have an antagonist, not every movie has external stakes.
If you look at this article -?http://www.scriptmag.com/features/write-logline?- then you'll see the highest rated scripts on the Blacklist have very vague loglines that break most of the rules that dpg talks about.
The one thing, I would say about your logline specifically is to cut it down to a clear, easy to follow sentence.