A barefoot farmer is making his way through a forest.

Quiet drops of rain tumble steadily through the night, picked out in the light from his torch.

The rusty machete he holds isn’t for cutting down vines or chopping away stubborn branches - it is a defence against thieves.

Lots of other men - farmers like him - are out in the rain, patrolling the forest. For the past three months, they have left their homes every night and made the long journey into the plantations to protect their crop.

But this is not an illegal coca plantation, or anything like it. In fact, these farmers are growing a crop whose name is a byword for something boring.

The men need weapons to guard against robbers who roam the countryside looking for one thing - Madagascan vanilla.