After one fateful PTA meeting, four young mothers—Lynne, Mary Kay, Beth, and Carol—discovered they had more in common than they ever thought possible. Meeting once a month, the women would share laughs and secrets, toasting to their blossoming friendship with the clink of their sacred martini glasses. Two years later, when Lynne passes away suddenly, she leaves behind one simple request: that her old friends sort through her belongings. The women reunite to rummage through her closets, and buried deep within Lynne's lingerie drawer, they find an envelope addressed to their little society... Inside is a letter that reveals Lynn's shocking secret and last wish, sending the women on a life-changing journey that will reveal to them that nothing is more powerful than the will of a true girlfriend—and a good, strong martini.