BBC News, London
Concealed behind an anonymous door lies a unique charity - where secret cameras and covert evidence gathering are preferred to street collections.
Now the organisation is looking for members of the public to get a taste of undercover work. BBC London took a look around its base in Upper Street, Islington.
The EIA used hidden cameras to film these tiger skins for sale in Tibet
For 25 years the Environmental Investigation Agency (EIA) has set up fake companies to catch international wildlife crooks trading in endangered species.
At times you could almost be forgiven for thinking you were in the office of a normal charity.
The background noise is the quiet murmur of work getting done, the clicking of keyboards and the whirring of printers.
In the kitchenette cupboards overflow with instant coffee and tea bags, while a "safety in the workplace" sign dangles on a neglected notice board.
But then you begin to see the clues.
An entire bookshelf is stacked with Lonely Planet guidebooks - from East Africa to China and Indonesia.
Thousands of crudely-bound dossiers are piled up with names like 'Rhino, musk rat and other cat reports'.
A hefty volume is entitled 'The Voluntary Sector Legal Handbook' (which given the charity's brief must come in pretty handy.)
And upstairs, in a scene resembling Q's laboratory, scores of tiny digital cameras are installed in handbags.
"The idea was to do something no charity had done before," said spokesman Mike Durham.
"We don't just make noise - we do proactive work and name names. We actively go after the wildlife criminals."
Undercover investigator Julian Newman has spent more than a decade posing as a trader in valuable commodities to expose crooks.
He said: "You have to be a good liar and keep calm.
"The smuggling organisations are powerful - they will use violence against you.
"Colleagues have been beaten up and had guns held to their heads."
He added: "We have to minimise the risk - because we don't have any back-up.
"If you find yourself in trouble halfway down a river in the Borneo jungle you are suddenly a long way from home."
Now the charity is offering three members of the public the chance to experience the nervy thrill of undercover work.
'James Bond feel'
For safety reasons, the winners of EIA's draw will not be able to join the frontline hunt for ivory smugglers, tiger skin traffickers and toxic waste dumpers.
But they will be briefed on using the charity's high-tech surveillance equipment, then let loose to covertly film London life to experience some of the charity's evidence-gathering techniques.
After training, the participants will be asked to sign a disclaimer confirming they will not use the equipment for any anti-social or illegal activity, the charity said.
EIA fundraiser Edward Cowdrill, who came up with the idea, said: "We were saying to ourselves, what exactly is exciting about EIA?
"Then we realised the answer is 'everything we do'.
"So a couple of our investigators have volunteered their time - and the three winners will get the full undercover experience."
He added: "There is something exciting about undercover work because it has that James Bond feel - but EIA actually make a difference."
Would-be undercover investigators can enter on EIA's website before 30 September.