This film would have failed miserably if the actor who played Christian couldn't act. Happily, Peter Marshall is truly convincing as a father in severe mental pain. An early scene, where he confronts the distributor of his daughter's film, sees him change from a slightly dubious agent, to having a worrying edge as he starts to ask about the process of the filmmaking, and finally to out and out savageness as he knifes his prey in the neck. His range is even greater than that though, because the scenes with Alice show a tender fatherly side. A very assured performance all round.
For the majority of the film, the violence is kept off camera. This didn't stop me from wincing, crossing my legs and squealing like a baby at a certain scene of middles abuse. Actually, two scenes of middles abuse. In the latter half of the film, there are some more graphic scenes of torture involving pincers, a blow torch and a nipple. Definite smarting was involved. The Horseman is never gruelling though and doesn't reach the dubious giddy heights of Antichrist in terms of injured privities.
The film does feel a tad too long. Even though the fights feel realistic rather than staged, there's maybe one or two too many in the final stages. The tone is spot on: intense without being unnecessarily nasty and mean-spirited. The underlying warmth of Christian keeps you engaged in the story. I can't say that I would want to watch it again but it is well worth watching once. If only for it having a villain called Derek.
If you like this you could also try:
Shuttle, Henry - Portrait of a Serial Killer, Kill List, The Machine Girl, The Girl With the Dragon Tattoo.