BBC Frontline Scotland
Frontline investigates the trade in illegal Chinese medicines manufactured using endangered animals such as tigers and leopards.
We had heard rumours for a while that Chinese pharmacies might be selling illegal products - medicines banned in the UK because they contain endangered species.
But we knew that no-one had ever found these kind of products in the UK outside of a few big English cities.
We took advice from campaign groups and decided that the easiest thing to look for here would be plasters containing tiger or leopard bone.
They are supposed to help with arthritis and muscle sprains. We felt they were products that someone who didn't know a lot about Chinese medicine might realistically ask for in a shop.
So back in December we started visiting a few traditional Chinese medicine shops to see what we could find. At first we really struggled. Nobody seemed to stock what we were after.
Then we realised we had been visiting the wrong places. We had concentrated on new stores that had sprung up over the past few years on the High Street.
We found those places knew the law and seemed to be sticking to it.
So we moved on and found smaller stores in more out of the way places. That's where we found the medicines that appear in the programme.
We then set up a couple of undercover stings to find out where the products were coming from. This was in some ways the hardest part of the investigation.
First we had to find a Chinese speaking investigator to pose as a potential bulk buyer. We sent her in with the cover story that she was thinking of opening up a medicine business.
There was no guarantee the targets would trust her enough to admit how the medicines were being brought into the UK.
But it worked - and the trail opened up by the sting took us to China and some shocking discoveries about new threats to the tiger's global future.
It is worth pointing out that most of the pharmacies we visited didn't offer illegal products - but a significant minority did.
And the worry for anyone interested in alternative therapies such as Chinese medicine is that the people selling illegal products were often happy to lie about them to make a sale.
There are only 20 tigers left in China. And what we discovered when we went there makes it possible that tigers could be totally extinct in the wild in just 15 years.
That is a very big price to pay for an arthritis medicine.
To find out more watch Frontline Scotland: The Tiger Trail, on BBC One Scotland at 1900 GMT on Wednesday, 21 March.