I got locked out of my Gmail account last year. At first I wasn't worried; I'd thoughtlessly punched in a few variations of my password before it froze me out for too many failed attempts. But when I tried to go through Google's password reset process, things started to spiral.

As part of the procedure, I had to answer personal questions — sure, no problem, right? I know my birthday! Google also pinged my phone and backup email with codes to confirm who I was. Again, no big deal; I was able to enter them. But then came the verdict from Google: Even though I had successfully answered all its questions, it still couldn't verify I was me.

There is no stranger digital nightmare then being truly, completely, and helplessly locked out of your account. It's a fear that would have sounded absurd even 20 years ago, but is now the premise behind one of the best horror movies of the year, Cam, out Friday on Netflix. A techno-thriller that actually understands how real people use the internet, Cam probes the way we live now by taking the locked account scenario to its paranormal extreme.

Cam's pulse-raising first scene introduces "Lola_Lola" (The Handmaid's Tale's Madeline Brewer), a camgirl who dreams of making it to No. 1 on her hosting site and will pull any stunt to impress her dedicated viewers. Like the camgirls she competes against, Lola uses her webcam to interact and flirt with her regulars while they reward her acts of softcore pornography with tips (the script, it should be noted, was written by a former camgirl, Isa Mazzei). Off-camera, though, Lola is simply Alice, an ambitious entrepreneur gearing up to tell her mother exactly what she does for a living. When Alice tries to log into her "FreeGirls.Live" account one morning, she is met with an error message telling her that she used an incorrect password. When she tries to reset it, another message appears: "No account associated with this email address." Except Alice's account is already live, and a woman who looks identical to her has hijacked the stream. In an increasingly vicious war against, ostensibly, herself, Alice tries to wrench her account back from this new and terrifying Lola, who appears to be a living embodiment of her own online persona.

The whole premise would be silly if it didn't feel quite so real. There is a seamless fusion between Alice's online and offline lives, with the view toggling between her commenters, her broadcast, and the wider, omnipresent angle of the set she shoots on. The sense that you're merely observing online events play out is heightened by the way you'll probably watch Cam: on a laptop, with a browser tab opened to Netflix.

But the movie's intensity still really hinges on its premise: the near-impossibility of proving your real identity on the internet. When I was locked out of my Gmail account, I became increasingly desperate, willing to show Google anything — my ID, my passport, my birth certificate! — to get back into my email. But there was no customer service or appeals team to plead my case to (in fact, one of the most implausible parts of Cam is that Alice is able to contact a helpline). Google was adamant in its automated emails that it doesn't accept documentation of any sort to let you back into your account. I was hopelessly stuck.

Even the growing opportunity of biometric verification, which is widely perceived to be the next big thing in online security, is prone to errors, corruptions, and theft. "The fundamental trouble with biometrics is that they can't be reset," The Atlantic warns. "If the pattern of one of your fingerprints is compromised, that's fine; you have a few backups. But if they're all gone ... getting them replaced isn't an option." The same is true of face or eye scans. If something went wrong and your biometric data was intentionally or accidentally corrupted, it would be extremely difficult to convince anyone that you are who you say you are, when, for example, your irises no longer match the data description of you on file.

The strength of online security is a more typical fear in an era when major hacks and breaches dominate headlines. But with security's strength comes that new existential question explored in Cam: Who are you once you're divorced from your email correspondences, your text messages, your bank account, your social media personas? At what point are our online lives more real than our "real" selves? While this tension has been a cinematic obsession pretty much since the invention of the internet, Cam grounds it in a whole new realm of realism.

In the end, I was one of the lucky ones; I managed to prompt Google to reset my password after a month of frustrated tears. There are still many others struggling to wrest their control back: "[P]ease help me figure out how I can prove my identity," one such person begged on a forum earlier this year.

The narrative conceit of Cam wouldn't work if it didn't reflect on our own anxiety over the stakes — the followers, messages, addresses, schedules, documents, or rank we stand to lose. After all, if it weren't for how indispensable our digital identities are, there would be an easy solution to all these woes: Make a new account.

That we fight so hard to keep from doing so just shows how tangled up we really are.