The fourth season picks up right after graduation with the family and Emmett discovering Bay's impulsive decision - and no one is happy about it. Meanwhile, Daphne is determined to prove herself worthy of her switchster's sacrifice while also dealing with the challenges of a whole new world of college.

Senior year means big changes for Bay and Daphne, as the Carlton School for the Deaf receives an influx of hearing students who are not happy to be there. Daphne begins working at a free clinic as part of her probation and Bay takes an art class at a local college.

This season sees dramatic changes in the lives of the Kennish and Vasquez families as a result of the verdict in the baby switch trial. Bay enrols in an experimental program at Carlton for siblings of deaf students. Meanwhile, Daphne starts her own food truck business.

In the first season, the lives of Bay Kennish, who grew up in a wealthy family with two parents and a brother, and Daphne Vasques, who grew up with a single mother in a poor neighborhood, are turned turned upside down when they discover they were accidentally switched as newborns in the hospital. When financial difficulties arise, the Vasques move into the Kennishes' guest house, giving everyone a chance to get to know each another.

When everyone else mysteriously vanishes from their wealthy town, the teen residents of West Ham must forge their own society to survive.