Liz and Sarabeth were childhood neighbors in the suburbs of northern California, brought up as close as sisters by the suicide of Sarabeth's mother when the girls were just sixteen. In the decades that followed their relationship remained a source of continuity and strength. But when Liz's adolescent daughter enters dangerous waters that threaten to engulf the family, the fault lines in the women's friendship are revealed, and both Liz and Sarabeth are forced to reexamine their most deeply held beliefs about their connection.