(CNN)An air raid siren wails in a smoky London basement as cryptologists in military uniform are hard at work cracking codes.
Bar of the future: Can The Bletchley crack the code?
It could easily be a scene from World War II, except everyone's slinging back cocktails.
This is The Bletchley, a subterranean bar on the fringes of London's upscale Chelsea district that's been styled to resemble Britain's wartime code-breaking headquarters -- a world of Bakelite telephones, mind-boggling equations scrawled on chalkboards, and stiff upper lips.
The real Bletchley Park -- portrayed in the 2015 movie "The Imitation Game," starring Benedict Cumberbatch -- tasked prototype computers and the country's top analytical brains with cracking the Enigma code used by Nazi Germany.
Its namesake has a different mission: To perfect a blueprint for the bars and restaurants of the future.
The new bar is designed as an immersive experience. Customers are greeted as "agents" by actors role-playing military personnel. By solving puzzles with Enigma code machines, they unlock the formulas to cocktails created specially for them.
While The Bletchley's wartime England might seem a long way from an Albuquerque mobile meth lab and a place where folks get nude to eat, all three venues were created by Lyall using the same apparently lucrative business model.
Lyall says his company only throws opens the door to its venues once it's sold enough pre-bookings to justify taking out a rental lease. He says has a community of 150,000 loyal followers who sign up knowing they'll get more for their money than just food or drinks.
"The definition of luxury is changing for younger people," Lyall tells CNN. "It's not about the best cocktail or dish, it's about experience."
At his Bunyadi restaurant, which attracted a 46,000-strong waiting list for its three-month run in the summer of 2016, that experience was the opportunity to disrobe in candlelight and be served a three-course meal by semi-naked staff. At ABQ, still operating in a funkily decorated RV in East London and soon to open in New York, it's dressing in hazmat suits to "cook" cocktails.
The Bletchley concept -- retailing at about $37 per person -- seems equally popular, tapping into Londoners' apparently evergreen fascination with their wartime past, their passion for problem solving and their thirst for reasonably priced booze.
A lack of menus at the new bar is all part of the Lyall masterplan, forcing customers outside their comfort zone and encouraging them to engage in the role play that results in being served two bespoke drinks, in addition to the welcome cocktail they receive at the door.
"The factor of a shock is very important," Lyall adds. "We're bored, especially our younger generation. We're overloaded with information on our social media platforms and we don't really know what we like and don't like."
Lyall compares his business model to the increasing reliance by young people on rental accommodation in cities where they've largely been priced out of home ownership.
"Traditional hospitality is very different," he says. "You buy a lease on a place and before you know you've spent a million pounds, and you'll spend the next five years getting that back.
"We, on the other hand, because we've got a big community that follows us, we've got enough interest before the product is launched and we've broken even before we've opened the doors. And that gives us the flexibility to test."
Will it catch on? Hamish Smith, deputy editor of Drinks International magazine, says such temporary concept bars meet a demand and fit the economics of a wealthy city like London.
"Pop ups are indeed the future -- but only part of it," he says. "They are fun, appealingly finite and give young experience-seeking consumers the hit of something new every time they spring up."
Long-term though, Smith -- whose magazine compiles the annual World's 50 Best Bars list -- insists there's no threat to established luxury players from what he calls "inferior forms of the art."
"In terms of the elite end of the business, a pop-up doesn't cut the mustard. World-class bars are not just about cool design and theme-led concepts."
He adds: "Those bars with committed teams and a few years under their belt may not always be flavour of the month among the hipsters but they are built to last."
At The Bletchley, on a fully-booked midweek night in early spring, those experience-seeking consumers certainly seem to be enjoying their hit of something new.
"It's great, very creative," says Michelle Finnegan, a London-based accountant visiting the bar with two fellow French Canadians. "The puzzles force you to be very random."
Andy Barwood, on a date with wife Jane, loved it too. "Just great fun. We were struggling to decode the puzzles, and when we did, we got unusual drinks. But then we realized they were really good."
Katie Trump, an actress and host who works at the bar as "Agent Six," briefing customers on their code-breaking missions in the clipped upper class English tones of a wartime military officer, says even nervous guests soon warm to the immersive experience.
"You can sense those who are shy to the interaction," she says. "You give them some cheekiness and a twinkle and they're in."