Sixty years after she captured America's heart, six-year-old Eloise is still making trouble at the Plaza Hotel in New York City. Eloise is the central character in a series of beloved children’s books, written in the 1950s by Kay Thompson, who died in 1998, and illustrated by Hilary Knight, who’s very much alive at 90. Thompson, who at various points in her life was a radio personality, a vocal arranger at MGM, and a popular cabaret performer, amused her friends with the voice of a little girl called Eloise. One of those friends thought the character might make a good children’s book, and introduced her to a young artist named Hilary Knight. Knight says he and Thompson hit it off right away. “She was the most fantastic, interesting, funny, tough lady," he recalls with a laugh. "She was incredibly talented and I never had so much fun in my life.” They ended up working on four books together, and a new show at the New York Historical Society looks at the creators of the series. Life at the Plaza Hotel Eloise has an absent mother, a close relationship with her Nanny, her dog Weenie, her turtle Skipperdee and the staff of the Plaza Hotel, where she skibbles about and makes a lot of mischief. Jane Curley, the exhibition’s curator, says Eloise became part of the cultural zeitgeist. “She landed at the Plaza in 1955, in the midst of the staid Eisenhower era, when role models for women were [traditional stay-at-home moms] June Cleaver and Donna Reed. And all of a sudden here's this wild irrepressible six-year-old rushing around barging into things, getting into trouble. And she struck a chord.” In fact, Curley adds, “The Plaza was flooded with six-year-olds looking for Eloise coming in and saying 'is Eloise here?'” They still arrive, looking for Eloise. Plaza concierge Hatusumi Komiyali suggests they check the elevator. "If the elevator comes up really, really slow, that means she did it again. That she pressed all the buttons!" she says with a laugh. The Plaza celebrates its most famous resident, even if she's fictional. Children visiting the Plaza can have an Eloise tea in the Palm Court, with pink cotton candy, go to a store with all kinds of Eloise merchandise, and even stay overnight in the Eloise suite on the 18th floor, designed by Betsey Johnson. It’s a riot of pink and each guest has a personal experience, says the hotel's PR director, Ariana Swerdlin. “Whenever you come in, Eloise writes you a note.” Ten year-old Annie Clark visited the Plaza, dressed like Eloise, in a black skirt, white shirt, pink sweater and a red ribbon in her hair, and carrying a plush toy turtle, like Eloise's pet Skipperdee. “I think that I do kind of relate to her, because she lives in New York City. I can be mischievous sometimes," she admitted. "But not always, like her.” A book for precocious grownups The irony is that Kay Thompson never thought of Eloise as a children’s book. Knight points out its subtitle is “A book for precocious grownups, about a little girl who lives at the Plaza Hotel.” “To her dying day, she said it was not a child's book. It offended her, you know, that people considered it that.” Curator Jane Curley agrees. “She didn't like children very much and she would waltz into Doubleday's [book store] and pick up stacks of her books out of the juvenile section and plunk them down in the grownup section and then walk out.” The centerpiece of the new exhibition at the New York Historical Society is a large portrait of Eloise that Knight painted for Thompson’s birthday, in which the six-year-old is posing like English royalty. Curley says the painting hasn’t been displayed for 57 years. Thompson donated it to the Plaza, where it hung in the lobby, but it was stolen on the night of the Junior League Ball in 1960. The mystery of the missing portrait The disappearance made headlines, Curley says. “Walter Cronkite announced on national TV, 'Eloise kidnapped from the Plaza Hotel.' Kay offered a reward. There was a great amount of excitement but the portrait failed to show up.” Two years later, Knight got an anonymous phone call telling him the portrait was in a dumpster on New York's East Side. He picked up the damaged painting and put it in storage, where it’s been, until it was restored for this exhibit. But the mystery remains. Who took it? Curley thinks she knows. "I strongly suspect that this was Kay Thompson's best stunt ever. She was tired of Eloise. It was 1960, she'd taken the three books out of publication and only left the original book in publication. So, to have the portrait disappear was a great exit.”