A young child, the daughter of Spanish diplomats, disappears. It seems she has been abducted but no ransom note is received and the detectives Isaacson quickly discover that a nurse, Elspeth Hunter, is probably the kidnapper. They also discover that Hunter has been a little too closely connected with the death of three other infants. But what are her motives? She married a fortune, and although she is connected to some fairly rough villains this crime does not fit their modus operandi. Is it something as 'simple' as psychological disturbance due to her own inability to bear children, or something more sinister unguessed at.