This film, set in an expensive-looking boys' school somewhere undefined in the UK (Scotland?) was made by a South Australian group funded by their State. It could have been a really good film but, as it is, is merely "quite good".
The problem illustrated by this film is that it is always hazardous for a director to go beyond his cultural parameters. It is obvious that some of the film was made in the UK and most of the actors seem to be English, but the trains used as part of the plot are not of a type I ever saw in the UK; worse, the way the 17-year-old suspect is treated could never (I hope) happen in the UK. The young man is charged with murder, but questioned AFTER charge (a no-no in the British system), is kept in police custody for literally days without a lawyer or parent present and is questioned in such absence; he is brutally slapped by the main detective because he insults a woman psychologist who, by the way, also manages to offer the young man inducements and/or threats in order to extract a statement. Whisky Wow Wow! I am a barrister so sensitive to these things, but even so...
As to the story, it starts very well, but peters out a bit into rather facile plotlines involving the Knights Templar and Cathars, all good ideas but not being developed, really.
Pity, it could have been a lot better. Still worth watching, though.
PS: On watching it for a second times, I see that the locations credited were in Yorkshire and on the Welsh border, with some work probably done elsewhere (I still think the police station was in Australia somewhere, having lived three years there a long time ago).