The number of reported webcam blackmail cases has more than doubled in the past year, and at least four suicides in the UK have been connected to this form of sextortion, says the National Crime Agency.

The NCA's Anti-Kidnap and Extortion unit has seen 864 cases of financially motivated webcam blackmail so far this year, up from 385 for the whole of 2015. The NCA believes the true number is a lot higher, though, due to significant under-reporting. Most victims (95 percent) were men or boys; men between 21 and 30 represent the largest group, but boys between 11 and 20 were also a "substantial portion."

The four sextortion-linked suicides have all been men and boys—and again, that figure could be under-reported.

Webcam blackmail usually goes something like this: you are befriended online, perhaps via Facebook or a dating website; the criminal persuades you to do something lewd in front of the webcam; and then the criminal threatens to share a recording of those sexual acts unless you pay up.

There are various permutations of webcam blackmail—perhaps the criminal uses a fake identity to trick you into trusting them—but it's basically just extra-vicious modern-day sextortion. If you've seen the recent season of Black Mirror, the episode Shut Up And Dance explores one particularly gruesome variant: a criminal hacks into the protagonist's computer and records a video of him masturbating and then uses that video to coerce him into doing all sorts of crazy shit.

In response to this surge in reported cases, the NCA has issued new advice for victims of webcam blackmail: don't panic, don't pay, don't communicate, and preserve evidence. Basically, if you find yourself being blackmailed, you should go straight to your local police, who will "take your case seriously, will deal with it in confidence, and will not judge you for being in this situation." You should not pay the ransom, but if you've already paid, make a note of where it was collected from; if it hasn't been collected, cancel the payment. Don't communicate with the criminal; instead, take screenshots of any messages, suspend your Facebook account (don't delete it), and report it to YouTube if there's a video that needs blocking.

There's also a cheery video from the NCA, if you prefer:

Back in 2015 we wrote about one particularly high-profile case of sextortion: a worker at the US Embassy in London, over a period of at least two years, stalked, hacked, and extorted hundreds of women from his desk. He was sentenced to almost five years in prison earlier this year. There was also a curious case in the US, where a local news station was sued after it reported on a 14-year-old boy who had been webcam blackmailed: the TV segment showed an image of the webcam video (which included the boy's genitals) and the boy's name was included, despite the family asking for anonymity.