In what sounds like an "Oceans Eleven" caper, someone has stolen two 19th-century, gem-encrusted tiaras from the Missouri History Museum in St. Louis.
The crowns were from the city's storied and controversial Veiled Prophet Ball.
The last time anything was stolen from the museum was 17 years ago.
"This is not typical," museum spokeswoman Leigh Walters told Fox 2 in St. Louis.
During their routine, daily check of the museum galleries on Monday, employees noticed the tiaras missing from their second-floor display, according to the St. Louis Post-Dispatch.
The crowns were part of the museum's ongoing "Seeking St. Louis" exhibit that tells the city's story, from early influences of explorers and immigrants to the construction of the Gateway Arch and modern times.
Part of that history includes the Veiled Prophet Ball, an annual formal party hosted by the civic and philanthropic group called the Veiled Prophet Organization, founded as a "secret society" by the city's elite in 1878.
The ball takes place each December.
The elaborate invitation-only event today honors young women — typically college sophomores — for performing hundreds of hours of community service and, as in days of old, formally ushers debutantes into society. Last year's 62 honorees and their families racked up more than 3,000 hours of volunteer time on 34 service projects, according to the Post-Dispatch.
The highlight is the crowning of the "Queen of Love and Beauty," who is attended by a court of honor of "special maids."
Critics ding the event's white, "elitist" history and the odd presence of the fictional, mysterious "veiled prophet," who only twice over the years has ever had his identity revealed.
"In fact, to underline the message of class and race hegemony, the image of the first Veiled Prophet is armed with a shotgun and pistol and is strikingly similar in appearance to a Klansman," wrote The Atlantic in 2014, which noted the organization didn't have black members until 1979.
The ball drew fresh fire in 2014 against the backdrop of protests and racial unrest after Michael Brown was fatally shot by a white police officer in Ferguson, Mo.
Today the debutantes wear feathered crowns. But in years past, the queen and her court were given pearl necklaces or silver tiaras, sometimes so elaborate that the items became family heirlooms.
The two stolen tiaras came from balls held in the 1800s — an 1894 Veiled Prophet Special Maid’s Crown and an 1896 Veiled Prophet Queen’s Crown. They were described as gold and silver, encrusted with gems.
The crowns have been in the museum's collection since the 1960s and been on display since 2005. The museum did not say how much they're worth.
"Our resource protection and collections teams are working with the St. Louis police department," the museum said. "All evidence including security footage has been turned over to law enforcement."
The museum is also evaluating its security protocols, which museum officials said meet the standards required for American Alliance of Museums accreditation, officials told Fox 2.