It's like some sort of dark fairytale. A beautiful young woman marries the heir to the throne and starts to get thinner and thinner. Until one day we look and she's not there at all ...
Of course, for some time now we've all been noticing the vanishing act of Kate Middleton. But perhaps because of the disturbing echoes of the dramatic weight loss of her late mother-in-law Diana so soon after her ill-starred marriage we haven't liked to say too much about it publicly.
Besides, all brides deserve a honeymoon, including one from the Press, and the media has clearly tried to be sensitive to Palace concerns about the huge adjustment the Duchess of Cambridge faces in adapting to royal life.
Still, the news that she is now being held up as a role model on pro-anorexia websites - there are such things - does turn the spotlight inevitably onto the one area of her public life that most have shied away from commenting on.
If this was Cheryl Cole or Victoria Beckham we'd now be staring at pages of photos with dates across the top of them and dress sizes across the bottom, charting their shrinkage.
Of course, the Duchess isn't quite yet the total public property that those "celebrities" are. She didn't seek out a life in the limelight as such, rather it is an accidental consequence of who she fell in love with.
Nonetheless, there is no doubt that Catherine Middleton has not "always been" as slender as she is now and the understandable desire to look slim for her wedding day can't account for her still diminishing figure.
After all, if many brides find the strain of walking down the aisle the best ever diet, the honeymoon usually sees a swift return to their more usual form.
But Kate has continued to ebb away. Observers reckon that the young woman who was once a healthy size 10-12 is now a UK size 4 - or, as it's known in the US, Size Zero. Her clothes reportedly have to be altered to take account of her weight loss.
Friends have denied an eating disorder, blaming stress and travelling instead.
You could put all this down to newspaper gossip or that kind of inappropriate scrutiny of a female public figure that is never applied to their male equivalents. If it weren't for the obvious evidence of your own eyesight. Last Friday in Birmingham her Alexander Mc Queen outfit hung on her tiny frame.
Popular opinion has it that bagging a prince means you're set up for life. That what lies ahead are years of stardom without effort, an adoring public, a fabulous wardrobe, a lackey to meet every whim. Palaces, banquets, red carpets and beaches.
If it's true that it is stress that is wreaking this havoc with Catherine's body, the myth will have to be rewritten. Of course, it is a life of privilege but it is also one that is almost entirely to do with image.
If this was some celeb or actress who had suddenly struck it lucky after years of hoofing around minor stage shows, she might have had more resources to draw on in dealing with the role of future Queen.
For no matter how thorough the wedding rehearsals, briefings from courtiers and attentive the fiance, nothing could have prepared Catherine for the 24-7-365 scrutiny that high royalty acquires.
She is under floodlights every second of her life. The courtship, the engagement, the wedding, the first overseas tour. The milestones are ticked off one by one. The voltage increases day by day.
Sometimes it's trivial, sometimes deeply personal, but it's constant. Is she promoting British couture? Is she too high street? Will she have a baby soon? Imagine being Kate and Googling your own name.
She has to find words for the dying, undergo SAS training for personal protection, make small-talk with thousands.
It's no wonder the strain makes itself visible. Only a superhuman could breeze through those changed circumstances in life.
What we want is for Kate to get back to normal, a return to the sporty, fit-looking young woman William fell in love with.
At least that's one thing she can rely on that may not have been there for her late mother-in-law. No one can doubt the singular devotion of her prince.