The first hour and a quarter of this film was excellent! A lighthouse is a splendidly evocative venue for a horror film and this movie is clearly a cut above (no pun intended) the umpteen trashy American slasher flicks of the same genre. The tension builds at a measured and well-crafted pace, giving us solid characterisation and some quite remarkable scenes. The brilliant toilet scene in particular (veteran actor Paul Brooke playing a blinder) was absolutely Hitchcockian and the dream scene with Gemma Jones in flashback mode, was truly haunting. The gore is reasonably convincing and the tension palpable. But why oh why did the obviously talented director ruin the ending with a solid 10 minutes of nausea-inducing and borderline illegal strobe lighting? Sorry but that made it utterly unwatchable for me, so I cannot really comment on the denouement.
What a shame! All that hard work and good acting by a splendid British cast somewhat ruined by the ridiculous and irresponsible strobe effects. Was it meant to be a perverted joke, because the hero was epileptic? Whatever. It was very badly advised and obliges me to deduct at least a star from my rating.