Leo Song sues companies that make defective drugs. His wife, Nora is a fledgling mother of a psychotic toddler and is pregnant with a child whose paternity is uncertain. The couple, transplants to San Diego from New York City, volunteers to host a masquerade party intended to build community among the aloof parents of children at their son's preschool. An uninvited, masked woman shows up to the party and refuses to leave. She never removes her mask, and apparently she speaks no English. Speaking in Shanghainese, this stranger, who calls herself Bei Qi, tells Leo that she is his own grown daughter, she has just landed in the States from China, and she needs a place to stay.
While Leo's career hinges on messy litigation involving a scheming pharmaceutical giant, Nora's motherhood is threatened by the intrusion of this supposed daughter. Meanwhile, Bei Qi gets caught up in emotional troubles that rattle her plan. And when quiet domestic struggles sustain all the secrets and betrayal they can endure, the family uncovers a scandal that threatens the health and safety of small children who have been prescribed antipsychotic medication.