There is disturbing material, including descriptions of violence and torture of monkeys, from the start of this programme.

There's a horrific and disturbing trade in the torture of Macaque monkeys that are filmed and sold online. Rebecca Henschke follows the trade in these videos from the USA to Indonesia to the UK. Who is making them, who is selling them and who is buying them? Why is it that monkeys being put through unimaginable pain is so attractive that people are willing to pay to watch it? Rebecca confronts the people at the centre of this worldwide trade.