In early March, Princess Charlene of Monaco flew alone to an official engagement in her native South Africa, and has not returned.
Ever awash with rumour and intrigue, the star-studded Mediterranean principality has been left to guess when, or if, it will see her again.
The sparse bulletins that have trickled out of the 'Pink Palace', the royal family's 800-year-old fortress home, say that the princess developed a sinus infection and had to undergo an operation.
But her long absence follows reports of severe turbulence in her 10-year marriage to the realm's 63-year-old ruler, Prince Albert, and many in Monaco fear something deeper is afoot.
Last month, under growing public and media pressure for reassurance, Albert and the couple's six-year-old twins, Prince Jacques and Princess Gabriella, flew out to meet Charlene at an undisclosed South African location.
Official photographs showed the royal couple dressed in rugged outdoor clothes and bush hats, surrounded by dense vegetation.
In other photos, the twins were sitting in a tree, with blonde Gabriella displaying an outré DIY hairdo that came eight months after Charlene made world headlines with her own edgy semi-shaved hairstyle.
"I am so thrilled to have my family back with me," wrote 43-year-old Charlene on Instagram. "Gabriella decided to give herself a haircut! Sorry my Bella, I tried my best to fix it."
Albert, whose Grimaldi family has run Monaco since the 13th century, is seen in one pose giving his wife a bear hug, but the pictures offered few answers to the questions gripping the couple's subjects.
"Albert's one of the richest men in the world," says Riviera-based journalist Louis Ducreux.
"People are asking why he couldn't have chartered an air ambulance to bring her home, or even sent the royal yacht. The feeling here is that something else must be happening, and they're using her medical problems as a cover."
A veteran Riviera socialite adds: "Suppose she'd been taken ill in somewhere like the Middle East. Would they have let her stay there for seven months?
"Isn't it odd that she's supposedly unable to leave a country where her family and friends are, and has often spoken of missing?"
The concerns intensified when it was revealed that just days after her husband and children returned to Monaco, Charlene collapsed at her rented lodge near Durban and was rushed into hospital.
She was admitted, late at night, under a false name and amid tight security, and released – with few details of her condition – the following day.
The palace has tried to stay aloof from the gossip, but in August Monaco was sent into meltdown by a lengthy article in a French magazine, written by Stéphane Bern, a well-known authority on royal affairs and confidant of Albert, which strongly suggested that Charlene and the principality have had enough of each other.
Headlined 'Charlene et Albert au bord de la rupture?' ('Charlene and Albert on the brink of break-up?'), the piece noted that, for three months before Charlene's departure, the royal couple had not appeared together in public, and portrayed the princess as effectively living outside the royal set-up.
"In Monaco," writes Stéphane, "everyone has known for years that Charlene escapes from protocol at the first opportunity, splitting her time between Roc Agel [a royal family holiday home across the border in France], a house in Corsica loaned to her by friends, and private holidays in Turkey.
"Even when she lingers in Monaco, she doesn't stay at the palace, but at an apartment once used by Princess Stephanie (Albert's sister), which has been put at her disposal."
Stéphane went on to claim that Charlene had become a disappointment to the royalty-revering Monégasques, "who speak of her rages and her crazy moods, which change as often as her hairstyles".
"The people greatly admire the prince, but they have trouble feeling the same about this melancholic princess who, after 10 years of marriage, has never taken the trouble to learn French." In fairness, he adds that the princess has had a lot to put up with.
At the time of Charlene's departure, Albert was engulfed in a paternity claim by a Brazilian woman who alleged he had fathered her 15-year-old daughter.
The timing would have meant that the girl was conceived when the prince and Charlene were already dating.
The palace dismissed the claim as "a blackmail attempt" but old Monaco hands pointed out that Albert has already admitted to fathering two other illegitimate children – a son, Alexandre, by a Togolese air stewardess he met on a flight to Paris, and a daughter, Jazmin, by a Californian waitress.
The case was scheduled to be heard in an Italian court earlier this year but appears to have been quietly dropped. A spokesman at the Tribunale of Turin, where it was to be held, confirms it is no longer listed.
"The assumption here," says Louis, "is that Albert has made it go away."
Even without such embarrassments, Charlene has rarely seemed comfortable during her 10-year stint as Monaco's glamorous châtelaine.
At after deck cocktail parties or under the ornate chandeliers of ritzy bars and restaurants, the high-society set call her 'Princesse Tristesse' (the Sad Princess) – a reference to the fact that she rarely smiles in public.
In recent years Charlene's appearances have become fewer, and when she makes them she seems strained and distant.
A former Olympic swimming star, who met Albert at a watersports festival in Monte Carlo, Charlene has made little attempt to disguise the difficulties she has found in fulfilling a royal role.
"People say, 'Oh, why isn't she smiling?' she told a magazine last year, "but sometimes it is hard to smile.
"They don't know what is going on in the background. I do have a privileged life, but I miss my family and friends, and I'm sad that I can't be with them."
On March 12, the princess flew to South Africa, to attend the funeral of the long-serving Zulu king, Goodwill Zwelithini KaBhekuzulu.
During the visit, according to the Monaco palace, she contracted a sinus infection, and was advised to wait before flying home.
In an interview with a Johannesburg radio station – conducted from somewhere deep in the bush - Charlene attempted to explain the problem:
"It's the longest period I've actually been away from Europe, let alone from my children," she told the radio station host, Mandy Wiener, "but I'm FaceTiming them most days, and they've been here, and will be returning to see me again after my procedure.
"The reason is that I can't fly, otherwise I'll have a problem with my ears.
"It's taken time to address the problem. I can't go into details, but I can't force the healing, so I will be grounded in South Africa until the end of October. It's been wonderful to be back here.
"Africa will always be a part of me, it always has been. I'm always going to come home ... South Africa means so much to me."
The princess has been staying near the modest Johannesburg home of her parents, Mike, an office supplies manager, and Lynette, a sports coach.
Locals say she has been catching up with old friends and helping out at the wildlife foundation that bears her name.
Pictures of Charlene on an anti rhino-poaching patrol present a radically different image from those that regularly grace Europe's high-society glossies.
Her blonde hair is severely chopped and razored at the sides, her expensive jewellery replaced by ethic bangles; her face unmade-up and her gaze steely.
While most in Monaco accept that the princess has genuine medical problems – apparently stemming from cosmetic dental work she underwent last year – few seem convinced that this could have kept her away for so long.
One French newspaper consulted a leading Paris ear, nose and throat specialist, who claimed never to have known of a patient being unable to fly for so long as a result of a sinus infection.
Further doubts were sown by a report in the popular German magazine Bunte that Charlene had been house-hunting in South Africa, and – with the help of a wealthy businesswoman friend, 47-year-old Colleen Glaeser – was setting up a company to run her personal affairs.
Colleen's Facebook page includes such sage advice as "life is short; spend it with people who make you laugh and feel loved" and "if you are just safe about the choices you make, you don't grow". One wonders whether Charlene has been listening.
Meanwhile Monaco's 45,000 citizens have been left to watch Albert attend the Olympic Games in Tokyo, Monaco Grand Prix and the Monte Carlo Gala alone.
For a place that has long depended on a glamorous female face to adorn its starry image, Charlene's absence is a serious problem.
Modern Monaco was essentially the creation of Albert's late mother, the glacially gorgeous Hollywood actress, Grace Kelly.
Rainer first met Grace at the Cannes Film Festival in 1955 and wooed her with all the raffish charm he could muster, but when they married a year later, Monaco was still a Riviera backwater, outshone by neighbouring French resorts and inhabited, as the writer Guy de Maupassant put it, "by the dregs of Europe".
Grace's arrival changed all that. The big name stars flocked to Monte Carlo, the high-rollers returned to the old Belle Epoch casino, and the yachts of super rich tycoons fought for space in the harbour.
As 'Graceland', Monaco became the single most fashionable place on earth, awash with money and teeming with celebrities – but the princess's shocking death in a car crash 39 years ago left a void that has proved impossible to fill.
When Albert and Charlene announced their engagement in June 2010, rejoicing swept through the sunny streets.
The bride-to-be may not have been a global celebrity like Grace, but she was attractive, wholesome, sporty and had saved Albert from what was looking like perpetual bachelordom.
The first signs that the match may not have been as perfect as hoped came with astonishing claims from within the royal circle that Charlene had tried to bolt on the eve of the wedding, and had only returned after a showdown meeting with senior courtiers at nearby Nice Airport, where she was awaiting a flight home.
Stories circulated that a deal had been struck, offering her a life largely free of royal obligation, if she would stay and produce an heir.
The twins duly arrived in 2014, and Charlene and Albert have continued – at least officially – to appear in public and speak warmly of each other.
On July 2 – their 10th wedding anniversary – Charlene issued a touching tribute to her husband from South Africa: "He has been the most incredible support to me.
"My daily conversations with Albert and my children help immensely to keep my spirits up, but I miss being with them. I can't wait to be reunited with them."
Monaco has long been a place of intrigue, where nothing is quite as it seems.
At its best, it is a romantic curio, a throwback to the days of raffish dandies, fortune-hunting bounders and blondes in mustard Bentleys swooshing between the Beach Club and the bar of the five-star Hôtel de Paris.
Its follies and scandals have entertained the world for years, but the realities of the modern world are never far from the surface.
One of the prime realities is that the place needs a royal love story to believe in.
Palace sources suggested Albert and the twins would stay in South Africa for around 10 days, but they left after only three or four, with no details given of their arrangements, or how they had spent their time.
Far away, in a place she has served without ever really belonging to, the passing weeks only fuel doubts about whether Monaco's missing princess will return.
Around the roulette wheels in the grand Belle Epoch casino, the high rollers aren't laying bets on it.
Read this story and more in the November issue of The Australian Women's Weekly - on sale now.