One night in 2023, Eric was scrolling on a social media channel he regularly browsed for porn. Seconds into a video, he froze. He realized the couple he was watching - entering the room, setting down their bags, and later, having sex - was himself and his girlfriend. Three weeks earlier, they had spent the night in a hotel in Shenzhen, southern China, unaware that they were not alone.

Their most intimate moments had been captured by a camera hidden in their hotel room, and the footage made available to thousands of strangers who had logged in to the channel Eric himself used to access pornography.

Eric (not his real name) was no longer just a consumer of China's spy-cam porn industry, but a victim.

So-called spy-cam porn has existed in China for at least a decade, despite the fact that producing and distributing porn is illegal in the country. But in the past couple of years the issue has become a regular talking point on social media, with people - particularly women - swapping tips on how to spot cameras as small as a pencil eraser. Some have even resorted to pitching tents inside hotel rooms to avoid being filmed.

Last April, new government regulations attempted to stem this epidemic - requiring hotel owners to check regularly for hidden cameras. However, the threat of being secretly filmed in the privacy of a hotel room has not gone away. The BBC World Service has found thousands of recent spy-cam videos filmed in hotel rooms and sold as porn, on multiple sites.

Much of the material is advertised on the messaging and social media app Telegram. Over 18 months, an investigation discovered six different websites and apps promoted on Telegram that claimed to operate more than 180 hotel-room spy-cams, capable of capturing and even livestreaming hotel guests' activities.

The investigation revealed how easily one could access these sites by subscribing for a fee, gaining access to multiple feeds showing different rooms. Subscribers to these channels often commented on the unsuspecting guests, with discussions often veering into deeply uncomfortable territory.

Despite strict laws against such surveillance, the allure and accessibility of this content continue to lead individuals into hidden-camera surveillance, perpetuating the cycle of victimization without recourse for those affected. Eric and Emily remain traumatized by their experience, adapting their lives in response to the fear of being recognized and the potential for their private moments to resurface.