Barbara Mertz couldn’t make it to Cairo for her 85th birthday, so Cairo came to her in Frederick. On Sept. 29, the queen of Egyptian mysteries, known to her legion of fans as Elizabeth Peters and Barbara Michaels, enjoyed a celebration fit for ancient royalty — with a very good sense of humor.

More than a hundred of Mertz’s friends and colleagues, some costumed as pharaohs, traveled from as far away as Chicago, Texas and Maine to pay tribute to an author who has published more than 60 books. Wearing a long black gown and jet-black wig, Mertz sat in a rattan throne, sipping a drink and smoking from a silver hookah like a character from “Alice in Wonderland.”

The Nile of life that brought her to this point is legend. By the time she was 23, Mertz had earned a PhD in Egyptology from the University of Chicago, but jobs in academia were scarce for young women. After writing a couple of popular histories of Egypt, she published her first novel, “The Master of Blacktower,” in 1966 and found her true calling. For more than 40 years, like Cleopatra, “she hath pursued conclusions infinite” in several popular series and dozens of stand-alone novels. Nominated many times for various mystery prizes, she won the Agatha Award in 1989 for “Naked Once More.” Now, like Agatha Christie, she has an award of her own: Malice Domestic, the association of mystery writers, recently instituted a prize named for her recurring heroine, Amelia Peabody.

Saturday’s party took place in the graciously landscaped yard of Mertz’s Hobbit-inspired farmhouse. A grand pyramid (c. 2012) marked the entrance. Early in the day, a live camel and a python dropped by to add Egyptian ambiance. Belly dancers entertained the guests.

Those guests included Mertz’s agent, her editor, her doctor, and half a dozen senior mystery writers, including Joan Hess, Margaret Maron, Dorothy Cannell, Parnell Hall, Aaron Elkins and Sharan Newman — a royal court of sleuths who have published more than 120 novels and speak of one another’s characters like members of their extended family.

Barbara Mertz receives guests at her Egyptian-themed 85th birthday party in Frederick, Md. (Ron Charles/The Washington Post)

After dinner — chicken, lamb and stuffed grape leaves — the party settled down (a bit) for an old-time radio play drawn broadly from Mertz’s Amelia Peabody series about the golden age of archaeology. The Egyptomania Theatre of the Air, complete with comically bumbling sound effects, was led by Broadway actress Barbara Rosenblat, who has been the voice of Mertz’s audiobooks for years. A chain smoker with an ironic elegance that seems almost an act of self-parody, Rosenblat brought down the tent every time she glared at the audience and announced, “I have a presentiment of impending doom!”

Toward the end of the evening, a dune-colored sheet cake in the shape of a giant open book arrived from Charm City Cakes in Baltimore. (Chef Duff Goldman, from the Food Network’s “Ace of Cakes,” is a legend of his own realm.) Triumphant music began, giant sparklers exploded from the cake, and a little plastic figure of Amelia Peabody slowly rose to the top of an icing pyramid.

Guests brought presents at their peril. The invitation warned that “anyone attempting to proffer a birthday gift of tangible value will be put at the mercy of Sobek, the Crocodile God, who has been known to rip out entrails.” Everyone knew with whom they were dealing.