Portrait painter Iris Grey arrives at Pitfeldy Castle in the Scottish Highlands, at the request of Baron Jock MacKinnon.

Jock has commissioned Iris to paint a portrait of his fiancé, an American socialite Kathy Miller, ahead of their New Year wedding. Kathy invites Iris into her confidence, as she's received a series of threatening notes asking her to call off the wedding. Iris begins to investigate, and when a body is discovered in the grounds of the castle, she fears for Kathy's safety.

With the wedding fast approaching, Iris tries to solve a mystery that is caught up in a rarified world of family feuds, romantic intrigue, buried secrets, and murder.