A record label has hired a private detective to trace jazz singer Madeleine Peyroux, whose album has been steadily climbing the UK charts.
Peyroux's album is expected to hit the top 10
The US singer has failed to turn up for any promotional work, according to Universal Classics.
It said this was not the first time she had vanished, spending seven years busking in Paris after the release of her debut album.
Record bosses said she was "proving impossible to track down".
Peyroux's voice has been compared to Billie Holiday, with the potential to become one of the biggest-selling artists of the year.
She released her debut album, Dreamland, in 1996 to rave reviews but soon ducked out of the public eye to spend her time busking on the streets of Paris.
On her return to the music scene she signed to independent label Rounder Records, which now has a licensing deal with Universal.
A Universal spokeswoman said: "She should be overjoyed with the album's chart position, but she has now returned to America and is proving impossible to track down.
"Anxious record company bosses and her management company have been trying to contact her for nearly a week to no avail. She has simply disappeared."
The company said it had gone "to great lengths to protect Madeleine from burn-out through too much promotional work".
"But it would seem that despite these efforts Ms Peyroux has had enough," said the spokeswoman.
"She is that rare thing, an artist more interested in her music than in the glitz and glamour of showbusiness."