Everything free comes with a price. But PreShow, a new company from a founder of MoviePass, wants advertising to be the only price of a movie ticket.

Launching a campaign on Kickstarter Thursday, PreShow is developing an app to earn you free movie tickets -- to any film in any theater -- if you watch 15 to 20 minutes of high-end advertising. Like a sponsored session of ad-free Spotify that you unlock with a special commercial, PreShow wants to make going to the movies feel like free.

But PreShow hinges on what some may consider a cost and others consider a bargain: facial recognition. 

"If it weren't for facial recognition, I don't think we could still do it," Stacy Spikes, the founder and chief executive of PreShow, said in an interview last week. "If not, they could game this all day long."

Forgoing a password, PreShow's app will only unlock with your phone's facial recognition technology. And while you're watching the ads to earn that free ticket, your phone's camera monitors your level of attention. Walk away or even obscure part of your face? The ad will pause after five seconds. 

Facial recognition is already playing an ever-growing role in your life, for good and for ill. It's the technology that helps you find all the snapshots of a particular friend in Google Photos; it's central to how some smart-home technologies aim to make your life simpler. But it also could scan your face at an airport or concert without your knowledge. As face recognition advances and spreads, it opens up a host of privacy and security worries. 

But without facial recognition, PreShow wouldn't be possible. 

"We had two problems to solve: We didn't want people creating dummy accounts, and we're dealing with real currency at the end of the day, so we needed to uniquely lock it," Spikes said. "Facial recognition at the phone level is just a year and a half old. You couldn't do this company two years ago."

Watching a phone watching you

PreShow uses facial recognition for identification and verification -- it needs to make sure you're the only person who can open the app (and you only have one account) and that you're actually watching those ads while they play. 

The unlocking mechanism is built upon your phone's existing face recognition capabilities. In a demo of PreShow, Spikes unlocked the app via his iPhone 7's front-facing camera. 

The viewing accountability part was harder. PreShow built its app so that when you're watching an ad, a green border glows around the edge of the video. So long as the front-facing camera can recognize that your face is looking at the screen, the border stays green. Walk away, direct your head away from the camera or even obscure part of your face, and the outline turns to red in the demo. After five seconds of red, the commercial automatically pauses. 

Like the app itself, PreShow's privacy specifics are still in flux. A private beta launch of the PreShow app is slated to start in July, with Kickstarter patrons being the first to use and share it. The company hasn't specified when it will be made available to the public at large. 

So, for example, PreShow hasn't finalized an end user license agreement yet. Yes, that's the "fine print" digital contract you always sign, probably without reading, whenever you sign up for a online service. But it would be where company officially spells out how it plans to use its facial recognition. 

The beta testing will be key, PreShow says, as it will be working on terms and conditions during the beta as it learns from user feedback. Once PreShow starts letting people into the beta test, it will be sending out more details about the user experience overall, including the facial recognition technology, it said.

Among the specifics PreShow would define today: The app will not be recording anyone as they watch, and it won't be sharing personally identifiable data to third parties. For its advertising partners, it will provide aggregated and anonymized data -- as Spikes put it, "they will not get anything other than a 30,000-foot view" of your activity. 

That 30,000-foot view will be based on basic demographic data you volunteer in the signup process. PreShow plans to ask you to identify your age, geography and gender so it can provide the aggregated demographic details that advertisers want. Will PreShow use facial recognition to verify that you were honest in identifying yourself as a man or a woman, for example? Facial recognition raises questions that PreShow will need to be address in black-and-white disclosures.

Spikes notes that in other ways, this kind of advertising is more sensitive to your privacy.

"What's happening today in media is the brand will buy a bunch of data, and then it will trade that data and it will follow you around and it will embed cookies -- it's a covert art," he said. "This is much more out in the open."

A MoviePass second act

Spikes was a co-founder of MoviePass in 2011, but he parted ways with the company after Helios and Matheson Analytics took control of it and introduced the $10-a-month, unlimited-daily-ticket deal. That unlimited deal that was beloved, and new members subscribed in drove -- until it became notorious. The initiative drove MoviePass to the edge of insolvency, triggering the company into a farce of constantly changing prices and benefits.

But before MoviePass unraveled, Spikes (as a PreShow representative put it) "was let go."

"You'd have to ask MoviePass about specific rationale for the decision, but Stacy didn't agree with the direction the company was going. That likely had something to do with it," the spokeswoman said. "He started working on PreShow soon thereafter."

Like MoviePass, Spikes hopes that PreShow can help pull cinema into new ways of doing business.

"If the innovation is there in a big way -- that is, universal from the consumer standpoint -- it helps cinema to leap forward. And hopefully, making moviegoing possibly free will radically do that again," he said.

But unlike MoviePass, where the cost of movie admissions for a single member could far outstrip the revenue their subscription brings in, PreShow won't be a business that operates in the red, Spikes said. The consumer pays his or her own way by virtue of watching the ads, whether the company's user base is 3,000 or 30 million. 

Thursday's Kickstarter launch will fund the company's initial free-ticket campaigns. In addition, PreShow has funding from an unnamed angel investor who is a former wireless industry executive with an interest in cinema. 

Spikes also raised the possibility that earned points in PreShow could be applied to buy products, like a pair of tennis shoes, in addition to movie tickets. 

The advertising in the app will be video made by brands with integrations in movies -- think Dodge putting its cars in the Fast and the Furious franchise of movies. It would also include behind-the-scenes-style videos involving brands and films -- imagine a featurette about Brie Larson's training regimen for Captain Marvel that's sponsored by a fitness company.

Not all advertising in PreShow will earn you credit. When advertising is in new release, it will run a promotion that earns credit, but once that inventory is used up, the video will go to a libary where it's still viewable without any rewards. For example, when a new Marvel film is coming out, the advertising for it may drop into PreShow two weeks in advance. The company earns enough ad dollars for, say, 100,000 tickets. But once the promotional inventory "sells out," the credits are gone but the content will remain. 

"There will be scarcity in the ticket, but the advertising will have an afterlife," Spikes said. 

But the price of a PreShow free movie ticket isn't just advertising, it's facial recognition too. It'll be up to you to decide whether that price is a steal.