A border can be many things. The Orontes river in Syria is a sharply defined border, at some point reconstructed into a channel cutting through flat fields and farmland. Now, on the one side there is the divide Free Syrian Army. On the other side, Assad loyalists and government troops. The river is more than a natural border separating them. In the past it also separated different people who saw each other as different but still neighbour and countrymen. Now these neighbours have turned into enemies, us and them, as a result of the ongoing war.

Olly Lambert’s film Syria: Across the Lines – Channel 4 Dispatches looks at these divides and it sometimes crosses it, showing the sectarian nature of the conflict; one that is their as a force of nature but one that is the result of grievances, losses, emotions and deliberate manipulations. The film starts with a young men who switched sides and left the Syrian police. Lambert also shows life in no man’s land between the opposing sides.

Award-winning documentary maker Olly Lambert has spent weeks living deep inside Syrian territory – with both government and opposition supporters – to explore how the two-year-old conflict is tearing communities apart. This unprecedented film witnesses first-hand how the country is collapsing into a sectarian conflict and faces a bleak future.

For five weeks he lived in the Orontes River Valley in rural Hama, an almost entirely unreported front line that is gives a chilling prospect of what Syria could become. His film is a graphic and unflinching portrait of a society cleaving apart in the face of dwindling international support, escalating violence and a growing mutual desire for revenge.

It is a depressing film.

The whole thing: