Captain Gregory's, a bar hidden within the Sugar Shack doughnut shop in Alexandria. (Salwan Georges/The Washington Post)

Charles Koch can always tell when it’s someone’s first time inside his restaurant.

A friend probably told them to swing by for a drink, but all they see is a fast-casual eatery with a food menu that's suspiciously lacking in cocktails. "They'll come in looking lost," says Koch, a managing partner at the 14th Street newcomer Chicken + Whiskey.

That’s when he points them toward a walk-in refrigerator door in the back, where a watering hole is tucked away in plain sight.

Several calling themselves speakeasies have sprung up across Washington over the past few years, only to reveal themselves as merely retro bars that anyone can get into. Then there are real clandestine bars — ones that require an invitation from someone in the know. In another category still are the places so mysterious, few are even aware they exist.

For those looking for an adventure, hunt down these hidden spots, ranked easiest to access to most difficult. Have fun, if you can get in.

Chicken + Whiskey managing principal partner Kris Carr saws a block of ice in the restaurant’s back bar. (Deb Lindsey /for The Washington Post)

Walk inside this 14th Street spot dishing out South American-style rotisserie chicken, and you can grab a seat at the hidden bar lurking behind a refrigerator door without a reservation or calling ahead. From the name, you can guess which spirit the bar is heavy on (more than 90 bottles to choose from), along with stiff cocktails, beer and wine. Clusters of lightbulbs illuminate a sleek wooden bar, and guests are encouraged to rifle through the owner's record collection and play a tune. The entrance is so discreet that some commenters on Yelp have complained that the restaurant's name doesn't make sense. More room for the rest of us. 1738 14th St. NW. 202-667-2456.

Nocturne is housed inside the basement of the Sugar Shack doughnut shop in Shaw. (Alexis Jenkins)

To access this trippy, 17-seat bar tucked beneath the Sugar Shack doughnut shop in Shaw, you need to make a reservation online. An elevator leads to the basement, where you can sidle up to a blue-lit bar with a near-blinding, illuminated marble countertop. The menu features a dizzying mix of color-coordinated squares, each representing cocktails organized in such categories as carbonated, seasonal and rich (three for $35). Standouts among the bizarre-yet-creative offerings include the Nuoc the Casbah, made with ramen noodles and a savory broth of fish sauce, coconut milk and scotch. The Duck Season has brandy, duck fat, prunes and vinegar. Playing it safe? Opt for a glass of wine or one of the three beer options. 1932 Ninth St. NW. No phone.

Bartender Megan Kyker opens the door leading from Sugar Shack, a low-key doughnut shop in Alexandria, into Captain Gregory's. (Salwan Georges/The Washington Post)

From the same team as Nocturne and also housed within a Sugar Shack, this nautical-themed bar requires an online reservation as well. But if you're in the shop and spot a raised whiskey flag, give it a pull: The flag acts like a doorbell, ringing a bell on the other side. If there's room — only 25 guests are allowed at a time — you'll be admitted through a false door. The bar, decorated with lobster cages, oars and a ship's wheel, is named after a seafarer who supposedly invented the hole in doughnuts. The food menu includes seafood-heavy small plates, while the classic-leaning cocktails include a daiquiri ($13) and a brown-butter old-fashioned ($16). 804 N. Henry St., Alexandria. No phone.

In a true act of diplomacy, the French Embassy offers the public access to its bar, cafeteria and fine-dining restaurant — but, like getting a passport, you have to jump through a few hoops. Start by filling out an application online and submitting a photo for a free membership card. Once you pass a security check, you and up to three guests can visit the embassy's eateries, including Cafe Descartes, a casual bar with a small seating area and foosball table. At happy hour, on Fridays, you'll have a chance to rub elbows with diplomats and practice your French with a $4 beer in hand. For the elevated experience, head to Au Petit Bouchon, where Bordeaux-born chef Mark Courseille serves refined French dishes. You better believe the wine list is well curated. 4101 Reservoir Rd. NW. 202-944-6000. Open Monday through Friday 8 a.m. to 5 p.m. Happy hour Fridays 6 to 8 p.m.

Sidecar, a bar beneath P.J. Clarke's, calls for a reservation or a membership card for admission. (Sidecar)

Beneath power-dining hot spot P.J. Clarke's lies this prim underground bar, with vintage-book-filled shelves, white linen tablecloths and walls lined with portraits of every U.S. president. Given its secret status, crowds can be thin. Guests can make a reservation by phone or apply for a free membership card, which unlocks a sliding door that leads to the basement. To become a member, submit your business card along with an application. (Questions include: "What is your most perfect meal?" and "What is your preferred drink?") The space is often rented for private events, so call before showing up. 1600 K St. NW. 202-463-6630.

Behind that refrigerator door, guests will find Backroom Bar, a glitzy lounge that’s twice the size of the sandwich shop. (Deb Lindsey /for The Washington Post)

Backroom Bar

Behind a walk-in refrigerator door in Capo's Delicatessen in Shaw, there's a glitzy lounge that's twice the size of the sandwich shop. Dubbed Backroom Bar, the room has leather tufted banquets, a huge chandelier and clusters of plush sofas that encourage conversation among guests, who are often dressed to the nines. The only way to get in is to be invited onto "the list" by an existing member, or be with a friend who is. Once you're on the invite-only roster, you can add up to three friends. A few small bites are available, but you're probably there for the shooters ($9), copious cocktail offerings ($12.50) and bottles of champagne ($25-$300). It's also the perfect place for a party: Backroom Bar can be rented for private events; to dial up the secrecy factor, many hosts implement a password system. 715 Florida Ave. NW. 202-910-6884.

Bar 3100 at the British Embassy

If you're lucky enough to be invited by an employee of the embassy to this pub, you can sip $3 beers — such as Boddingtons, Newcastle Brown Ale and Fuller's London Pride — among friendly chaps. The bar, part of a mixed-use room used for private events such as the embassy's popular annual Halloween costume party, is sparsely decorated, save for a life-size statue of a Beefeater and a portrait of Queen Elizabeth II. One Friday a month, a small group of employees volunteer their time and open the bar to staff and friends. World Cup watch parties and charity trivia nights draw big crowds, but if you're really lucky, you'll be there when the embassy's resident band, Diplomatic Incident, performs. 3100 Massachusetts Ave. NW. 202-588-6500.

Ernest Hemingway Room at the Cuban Embassy

Hoping to snag a stool at the mojito-slinging, Hemingway-themed bar rumored to be within the Cuban Embassy? Good luck. To find out how, this reporter did just about everything but climb the metal fence that surrounds the property and bust down the door, including emailing and calling the embassy daily and asking sources at the State Department and local Cuban advocacy groups for insight. Even an in-person visit — a ring of the doorbell at the gates — resulted in only a business card that led nowhere. A Washington Post reporter who attended an event at the embassy in 2015 confirmed the bar's existence at the time. But that's as close as we got. Sorry, Rose's Luxury: This is officially the hardest seat to get in town. 2630 16th St. NW. 202-797-8518.

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