The Angel Of Darkness: Number 2 in series

A year after the events narrated in The Alienist, the cast of characters from that novel are again brought together to investigate a crime committed in the heady days of New York in the 1890s, but this time narrated by the orphan Stevie Taggert. 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?