John Thomas MacKenzie would much prefer to spend his remaining years just "tending his garden" at his estate in Spanish Florida, surrounded by his two tall sons and his lovely daughter Rebecca (whom all but her father call Becky). Unfortunately, the Empire of Great Britain and the young United States intrude on his plans.

The English hope to cause an Indian uprising and seize the Spanish colony as a base for an invasion of their 13 lost American colonies. Against his will, MacKenzie is drawn into the turmoil by an American naval lieutenant and his crew who have been secretly sent by their government to try to thwart the British scheme.

As if that weren't trouble enough, they encounter in the process an old enemy of MacKenzie's, a former pirate known as Dread Jamie Tyrone. When Tyrone sees Becky it's love at first sight -- on Tyrone's part. He kidnaps the young woman and plans to spirit her away to Ireland where she will be forced to become his wife.

A chase ensues by both land and sea as MacKenzie and a companion seek to rescue his daughter while the Americans hurry to warn the Spaniards of the danger from the British. A resolution finally occurs at sword point in the vast untamed wilderness of Spanish West Florida.