The film begins with a voiceover from one of the main characters, so the story is presented in the past tense. You'll forget all about the voiceover foreshadowing that it will turn out ok for the boy and his mom.
Within 5 minutes, you dislike Phil, and within a half hour you HATE him.
Cumberbatch plays such a cruel man so beautifully, you'll want to get up and leave. Just at that point when you can't stand it anymore, the film makes a 180.
This isn't grandpa's western.