On the evening before his marriage, Sinclair loses a precious curiosity from his collection: an amethyst box, containing a tiny flask of deadly poison. He suspects that this poison is in the possession of either his betrothed or her cousin.Sinclair and his friend, Worthington, try to recover the box before the poison can be administered...

Anna Katharine Green (November 11, 1846 - April 11, 1935) was an American poet and novelist. She was one of the first writers of detective fiction in America and distinguished herself by writing well plotted, legally accurate stories. Green has been called "the mother of the detective novel".