On the frontlines of the battle of the bulge, otherwise known as trying on bathing suits in the communal dressing room at Loehmann's, freelance writer Jaine Austen makes a new friend--a wannabe actress named Pam--and gets a new job: sprucing up Pam's bare-bones resume. Their feeling of connection is mutual, so Pam invites Jaine to join The PMS Club-a women's support group that meets once a week over guacamole and margaritas.

But joining the club proves to be more a curse than a blessing for Jaine. Though she is warned that Rochelle, the hostess, makes a guacamole to die for, Jaine never takes the warning literally. Until another PMS member, Marybeth, drops dead over a mouthful of the green stuff after confessing she is having an affair with Rochelle's husband.

While Rochelle and her husband are the obvious suspects, everyone at that night's meeting is under suspicion, including Jaine. So, instead of dishing dirt with The PMS Club, Jaine has to dig up dirt on the surviving members. And soon it becomes clear: someone in this club thinks getting away with murder should be a privilege of membership...