After losing his job as a paralegal, Sam Stein suffers a panic attack and stumbles into a job babysitting his psychiatrist's three granddaughters. The girls' mother, Dianne, is an actor whose once-promising career has stalled; she's in a difficult marriage to David, a rock bassist. When David goes abroad on tour, Dianne and Sam discover an easy rapport as well as a shared history of mental illness. Sam joins Dianne's family to babysit for the summer on Martha's Vineyard, and he ends up in a house with the woman he pines for, her husband, the three kids, and all four grandparents, including his psychiatrist.