Anna worries that her brother Nick does not have good health insurance, so she writes a contract stating that if he mows her lawn on the last Saturday of every month she will buy him an expensive insurance policy that he could not otherwise afford "for at least the next six months, and longer if necessary." The next week, Nick gets a great job at an investment bank, which provides him health insurance coverage. Anna congratulates Nick and revokes the deal. The breach of contract infuriates Nick, who sues his sister. What will result?