Tessa macFindlaech is sent from her mountain home in the Scottish Highlands to live with her uncle, Thane Macbeth, and perhaps find a husband who'll abide her outspoken ways. When an Englishman visits Macbeth's castle, Tessa distrusts him and isn't shy about saying so. At the same time, she feels an attraction to Jeffrey Brixton she can't deny.
Three weird women Tessa once met on a hillside predicted that she would travel to England. Though she rejected the odd statement, they were right, for Jeffrey kidnaps Tessa and takes her there.
Macbeth becomes "king hereafter," as the crones predicted, and Tessa's adventures prove they are not simply madwomen. She must take care, though, for their words have meanings that are "double, double," and they result in--you guessed it--"toil and trouble!"