After being diagnosed with melanoma, Cathy decides to build a pool in her backyard, much to the chagrin of her older curmudgeonly neighbor, Marlene. Cathy’s son, Adam, plays pranks on her while her husband Paul tries to get back in her good graces. Cathy also tries to reconnect with her willfully homeless brother Sean, and devises a weight-loss plan for Andrea, one of her summer school students.
Cathy learns from Dr. Todd just how little time she has left, and for the first time in her life, starts to appreciate her body. Paul tries to make sense of his wife's request to live apart for the summer by signing up for couples therapy. Adam, desperate to get away from his "crazy" mom, attempts to sneak off to soccer camp without her knowing.
When Cathy's attempt to connect to the people closest to her fails, she signs up for a well-meaning but overbearing cancer support group. Adam rebuffs Cathy's attempts to connect with him, so she decides to put together a dinner party with Andrea, Sean and Daphne. Meanwhile, Paul tries to win back his wife's love with an elaborately romantic gesture. Marlene discovers Cathy's cancer secret in a most unusual way.
Cathy, eager to try on a carefree, impulsive persona, drains her 401K, buys a convertible and imagines what life would be like if she were Dr. Todd's girlfriend. At his therapist's urging, Paul reignites his passion for rugby. Sean goes to great lengths to knock out a tooth without the help of a dentist. Meanwhile, Adam gets caught stealing and is surprised when Marlene comes to his rescue, until he finds out there are strings attached.
Cathy needs a lump on her butt removed and someone to pick her up after surgery. She asks Marlene, who becomes disoriented - so Lenny picks up Cathy instead. Sean moves into Cathy's backyard because he got beat up on the streets. Paul and Adam win the local bathtub races. The event brings Cathy and Paul back together, but at the point of reconciliation, Paul confesses to an indiscretion with Tina and Cathy rejects the reunion. Meanwhile, Andrea breaks into the school and destroys the mural Lenny painted.
Cathy and Sean hit the open road to visit their dad. During the trip, Cathy tells Sean she has cancer. Sean falls apart at the news, so Cathy pretends it was a big joke. Adam gets drunk while under the supervision of Paul. Marlene finds Adam on the front lawn puking. Marlene will keep it a secret, but Adam is in further servitude to her.
Dr. Todd tells Cathy that she’s been rejected from the clinical trial. Sean sets up Marlene on a date. At a party, Adam gets into a fight with Andrea. Cathy and Lenny take ecstasy together. Paul catches Cathy and Lenny having sex. Paul gets too drunk at the dinner to celebrate his promotion, forcing Adam to drive home. Paul tells Cathy he wants a divorce.
Cathy’s unexpected visit to Andrea’s home yields many surprises. Later, Cathy seeks spiritual advice at church and while helping around the house. Rebecca calls it quits with Sean in order to reconcile her friendship with Cathy. Adam apologizes to Andrea. Paul sleeps with Tina. Cathy reveals to Paul she has cancer.
Paul seeks support from people at his work place, but gets more than he bargained for. Sean pulls away from Rebecca when it appears she’s getting too serious. Cathy, Marlene and Rebecca have a girl’s lunch at a strip joint -- which unexpectedly influences Cathy’s thoughts about her cancer. Adam meets a girl, Mia, at the bus stop.