Passing opens in Hartford, CT on Passover, 1988. Two women, Gretchen, and her younger sister, Emma, have recently lost their mother, Ruth, who was a survivor of the Holocaust. Gretchen, who is married and has a young daughter, has long since moved away from Hartford. Emma, on the other hand, is unmarried and has spent her adult life living in the family home with their widowed mother. As is often the case in such instances, there is great love between the sisters, but considerable antagonism as well. To make matters worse, they've been unable to locate a will. Gretchen wants to sell the house. Emma wants to continue living there. This basic conflict stirs up many other long-standing tensions between them. When Gretchen leaves to run some errands, Emma discovers a sealed envelope in a box. It's addressed to Gretchen in their mother's handwriting. Emma opens the letter and reads it, leading to a long flashback to 1945 and the end of the war, during which a dark and profound family secret is revealed. The play's final scene takes place in the present day -- in the very near future. Perhaps tomorrow. In it, the choices made by Ruth in 1945 and those made by Emma in 1988 result in the gravest of repercussions.