INCEST, adolescence and rainy grey beaches in Devon, England. That about sums up the material in actor Tim Roth's directorial debut, which is as powerful a movie as you're likely to see this year, and quite possibly the most depressing.

Adapted from the controversial novel by Alexander Stuart, the film is about a fifteen year old boy (Freddie Cunliffe) who thinks he has seen his older sister in the bath having inappropriate relations with their father, played by Ray Winstone. Facing opposition from his sister (Lara Belmont) he tries to establish the truth and then do something about it.

Roth does not pull any punches with the subject-matter and coaxes out some highly charged performances from his young cast. Their personal chemistry is what may persuade an audience to sit through some shocking and disturbing scenes, much of it in a windswept World War Two pillbox overlooking the beach.

Following his critically acclaimed part in Gary Oldman's "Nil By Mouth", Winstone has proved with this performance that he can act sensitive monsters as well as bullying ones. His character here is a loving father one minute, a manipulative sodomite the next. Tilda Swinton only plays a supporting role as the unsuspecting mother, but as always her onscreen presence is magnetic.

With this in the can, Roth can go to sleep at night knowing that he is more than Tarantino's glove puppet, a talented director in his own right. Like Gary Oldman, he has obviously been storing up a desire to tell something honest and bleak after all those escapist movie roles.

Roth has pulled off something special here, another piece of impressively gritty, thoroughly uncommercial drama that the British seem to specialise in when they're not trying to whore themselves to American audiences in period costume. The arthouse circuit will probably love it, but it hardly qualifies as entertainment.