Donnybrook it is a very dark drama, and well worth seeing.
Ex-Marine Bell has a wife who is trying to get off drugs and 2 kids (a boy & a girl). His plan to improve their lot in life is to enter the Donnybrook, a bare-knuckles free-for-all fight contest where the last man standing will walk away with a $100k prize.
The acting is superb, particularly Margaret Qualley (daughter of Andie MacDowell), who plays the sister of Frank Grillo's violent drug dealer. The characters in this film are very poor and struggle with violence, drugs, crime, all the things that are often common in the poorer communities across America.
The bulk of this film is Bell's journey from his home in a trailer park to the site of the contest, and it's not an easy or straightforward path that he travels. He gets to the donnybrook, but it's the last 15 minutes of the film.