Lena Dunham, Jenni Konner on how they cast Camping, from Jennifer Garner to Juliette Lewis

Lena Dunham and fellow Girls executive producer Jenni Konner have author Zadie Smith (White Teeth) to thank for their latest project, an adaptation of the British comedy Camping.

No, really: Literary royalty Smith was a fan of the 2016 hit and recommended it to Dunham, who immediately brought Konner on board as a co-showrunner. "I became obsessed with it," Dunham says of her limited series' source material. "It tuned in on what it looks like when people are separated from the world they know and love."

Dunham and Konner's (extra-American) version of Camping — which takes place just outside of L.A. — focuses on a group of couples gathering for a weekend off the grid. Some are friends. Others… not so much. Ahead, the creators break down the key guests for EW.

The trip's mastermind may be neurotic and controlling, but Garner imbues the character with an unexpected warmth. "Jen turned her into a sweetheart in a surprising way," Dunham says. "She's so charming, even when she's playing a hard-edged, tough, intense character."

Kathryn's eager-to-please husband is the reason for the "celebration" — he's turning 45 — but Walt would rather not be the center of attention. Tennant captures that struggle perfectly, Dunham says: "He's so versatile, and seeing him play someone so meek and stuck inside himself is a joy."

Free-spirited Jandice annoys Kathryn, and not just as an uninvited guest brought at the last minute by Miguel, Kathryn and Walt's spiraling, newly single friend. "She believes in herbs and crystals, but she's also a very lost soul," Konner explains. "So she covers it with her bravado and her beliefs."

Passive and quiet, Carleen is the opposite of her sister Kathryn. "A lot of people read that part as hippieish," Konner recalls of trying to cast the role, "but she's much more of an expressive child than she is a hippie."

Dunham and Konner cast this real-life couple after seeing their social media output. "We loved their Instagram stories," Konner says. "We took a chance that they would be funny and have chemistry together, and it really worked out."

The tough-talking, arms-wielding campsite owner has a soft spot not just for her wife, but also for her bizarre collection of guests staying the weekend on a Groupon rate. Everett may be, as Konner notes, "nothing like Harry," but her read on the character contributed heavily to how she's portrayed. "There's no way I can imagine the character without Bridget," Dunham raves.

Camping premieres Sunday, Oct. 14, on HBO.