Vicky Barton and her brother Johnny travel from Naples to visit the 1889 Paris Exhibition. They both sleep in seperate rooms in their hotel. When the she gets up in the morning she finds her brother and his room have disappeared and no one will even acknowledge that he was ever there. Now Vicky must find out what exactly happened to her brother.

Jean Simmons
as Vicky Barton

Dirk Bogarde
as George Hathaway

David Tomlinson
as Johnny Barton

Marcel Poncin
as Narcisse

Cathleen Nesbitt
as Madame Hervé

Honor Blackman
as Rhoda O'Donovan

Zena Marshall
as Nina

André Morell
as Doctor Hart

Betty Warren
as Mrs. O'Donovan

Eugene Deckers
as Day Porter
CinemaSerf
This is a cleverly constructed thriller featuring an on form Jean Simmons as the naive girl holidaying with her brother "Johnny" (David Tomlinson) in Paris at the time of the Great Exposition. Things take quite a mysterious turn on their first morning when not only has her brother disappeared - but ...