Summer was gone and Molly Main waited for Paul to help her close up the house they had taken on an island in the middle of a lake.
When the night train arrived without Paul and news came from the next island that Adah Capello, famous soprano, had been slain, Molly became uneasy.
She suddenly recalled that in her jewel box lay an emerald Paul had bought from the singer, an emerald with a horrible story of love and hate and revenge behind it.
With Nell Harmon, a neighbor, Molly waited for Paul. But it was the killer who came, instead, seeking Paul and the emerald.
So begins a night of haunting terror.