Mary Whitney, heiress to the Whitney Enterprises fortune, is an experienced sailor.  She was trained by her uncles where she grew up along the shores of Puget Sound in the state of Washington.  She has developed a psychic connection to Lake Superior which extends from the Nineteenth Century when some of her ancestors owned and logged part of the great forests of Northern Wisconsin.  She also has an interest in exploring her roots and her almost mystical feelings about the lake.  Married to a successful advertising executive, Michael Tanner, Mary has planned a sailing vacation to Northern Wisconsin, but Tanner is delayed at home in Seattle at the last minute. 

Arriving alone in Bayfield, Wisconsin, Mary meets a young woman, Liz Dosal when the two of them come to the aid of a sailboat carrying the victim of a heart attack.  Mary and Liz are able to prevent the sailboat from crashing into the marina’s gas dock and blowing up half the harbor.  The developing friendship between the two women leads to several short sailing trips into the Apostle Islands Lakeshore. 

Because of an earlier attempt on her life, Tanner has authorized a loose surveillance on Mary’s ex-husband, Edwin Tobias.  Tobias is a wealthy corporate raider from New York, who has sworn to get even with Mary for divorcing him.  When Tobias slips away from the watching detective, Tanner raises the alarm but is unable to reach his wife in the Apostle Islands.  Cellular telephone and radio service are chancy in this area of Northern Wisconsin due to iron and other ores in the ground and the lack of comprehensive service. 

Tobias, who has been spying on his ex, has hired a smuggler with a boat and crew to help him abduct Mary when she is alone on her sailboat.