Charlie is a playboy who's convinced that relationships are dead even though his sister, a therapist, tries to tell him otherwise. His best friends bet him that if he sticks to one woman for one month, he's bound to fall in love. Charlie takes the bet because he believes that he's immune to love, until he meets the beautiful and mysterious Eva. Charlie coaxes Eva into a casual affair but soon finds out that she has turned the tables on him, after realizing he wants a bit more from their relationship.