Quiet, animal loving Leonie Daniel, a high school Physical Education teacher, leads a double life, often standing in for her glamorous older sister, Zara, who works as a government agent. All Leonie has to do this time is spend a few weeks in Zara's lakeside cabin near Hot Springs, Arkansas, behave like Zara and avoid Adam Silverthorne, the man her sister is interested in.
Alas, Adam is immune to the beautiful Zara, but he finds Leonie enchanting. Adam discovers she is Zara's younger sister almost immediately, but in order to woo her, he pretends to believe that Leonie is Zara. Leonie is equally attracted to Adam, but she is certain that Adam would never prefer her over her dashing, outgoing older sister. Worse, some spies are shadowing her every move in the belief that she is Zara.
Adam makes no secret of his attraction, and Leonie sees nothing but heartache ahead, yet she is drawn to Adam in spite of herself. She decides a vacation affair will give them both what they want, and it will end when the vacation ends, with no hard feelings or recriminations. Or will it?