For hundreds of years the male members of the Kilcannon family have considered themselves to be the beneficiaries of distortions in the statistical distribution of chance, associating their most fortunate windfalls with visual distortions that they call “streaks.”

This belief has led to the accumulation of a vast heritage of superstitions — rules which, if broken, might allegedly terminate the privilege. The current heir, Canny Kilcannon, is anxious to dispose of this burden, but is unsure as to how far he can go in tempting fate.

When his father dies, his life is further complicated when a female beneficiary of a similar centuries-old lucky streak reveals herself to him. Lissa suggests that they attempt the ultimate experiment — to test the boundaries of their gift. Can they succeed? Or will they bring down upon them the “black lightning” of which both of their traditions warn?