Bay Kennish discovers during a biology class that she has a rare blood type which is different from her parents. Intrigued by her new discovery, Bay convinces her parents, Kathryn and John, to visit a genetic testing facility where it’s confirmed that Bay is not their biological daughter. There was a mix up at the hospital and both families took home the wrong babies. Days later, the Kennishes are introduced to their biological daughter Daphne and her mother Regina Vasquez. The Kennishes are surprised to see that Daphne is deaf. John and Kathryn immediately research ways to help Daphne and suggest the possibility of Daphne attending Bay’s private school, which doesn’t sit well with Bay. Regina is against Daphne attending the school but agrees to move her family into the Kennish house to deal with their new family situation.
The Kennish family invites Regina, Daphne and Adrianna over to breakfast, but since they’re in the middle of unpacking their new home, only Daphne goes. She is quickly overwhelmed with how fast they speak and has difficulty understanding. Meanwhile, Kathryn suggests Daphne and her family come to their weekly grill night, but she and John are secretly upset when Daphne gets a ride to school on Emmett’s motorcycle. John and Kathryn see their attorney about filing a lawsuit against the hospital. And Regina tells Bay about her time in AA and that alcoholism runs in their family. Kathryn and John talk to Regina about joining the lawsuit and also how they don’t like Daphne riding on a motorcycle. The three adults all get into a big fight about their parenting styles at grill night. Later, Kathryn, John and Regina all agree they can’t control each other’s parenting styles. Then Regina tells the Kennishes she’s not interested in pursuing a lawsuit. Bay escapes the madness to hang out with Ty, while Daphne escapes to hang out with Liam. While together, Liam and Daphne run into Liam’s friends who make fun of Daphne’s disability – and Liam does not stick up for her.
When attempting to figure out a way to answer questions about their newfound living situation, Kathryn encourages her family and Regina’s family to give a vague version of the truth. She’s not yet ready for the “switch” details to be made public. Liam tries to make up with Daphne, but she won’t have it. And when Daphne and Emmett are talking about the Liam situation, Emmett tells Daphne he would rather date a deaf girl -- and describes his ideal girl as someone who sounds a lot like Daphne. Later, John meets Melody, Daphne’s basketball coach, Regina’s friend and Emmett’s mom. John and Daphne bond over basketball, but he takes practicing a little too far. However, with John’s words of encouragement about basketball, Daphne decides to make up with Liam. Meanwhile, Bay is curious and asks Regina about her biological father but Regina and Adrianna both refuse to talk about him. Ty shows Bay around his neighborhood, where she could have potentially been raised. And Bay confides in Ty about wanting to know her biological father. Later, Daphne gives Bay a photo of Regina when she was pregnant with her – and it was taken by Bay’s biological father. Elsewhere, Kathryn gets Regina a job at her hair salon. Regina’s first client is Kathryn’s nosey friend Denise. Later, Kathryn reveals the switched at birth story to her friend Denise.
Kathryn host the annual benefit for the school at the house and soon the newly mixed family become the subject of Mission Hills gossip. And things don't get better for them all personally when Kathryn becomes jealous of John's new friendship with Melody. Also, Regina accepts an invite for dinner with one of Kathryn's best-friends ex husbands and Bay becomes finds it hard to accept that Daphne has started hanging around with Liam.
After learning that Bay has secretly been seeing Ty both John and Kathryn insist on having him over for dinner. Knowing that they're going to use the dinner to interrogate him, Bay tries to prepare, but she's nowhere near prepared for the secret Ty reveals. And Daphne's morals are tested when Toby ropes her and Emmett into a poker game, but it soon becomes clear that he may be in over his head.
Daphne struggles to fit in at her new school as she becomes the subject of gossip at Buckner Hall after an incident in cooking class. Elsewhere, Bay and Emmett grow close while doing some research into her father together. Also, Toby finds himself in serious trouble as he struggles to pay Wilke back the money he owes him which, leads him to do something that could get him in even more trouble. Kathryn takes steps towards getting to know Daphne more after a quite heated conversation with Regina by beginning to learn ASL. And the Kennish's learn that the hospital has withdrawn it's settlement offer and wants to take the case to trial.
After the Kennish's learn of his involvement with the stolen exam and a talk with Regina, Toby decides to turn himself in and not let Wilke take all the blame. Meanwhile, Bay and Emmett continue to bond in her hunt for her biological father and, Daphne learns of a life changing secret that Regina has been keeping from her.
As Bay and Emmett's relationship continues to get more serious she become conscious about his apparent love for Daphne. Meanwhile, Daphne is upset with Regina after learning the truth and spends the day hanging out with Wilke in her old neighborhood. During the Deposition, Kathyrn and John are blind-sided by what they learn and, later everyone confronts Regina over her lies and she comes clean about knowing all about the switch for the past 12 years and how. With no one but Toby willing to give her a chance she packs a few things and leaves.
it is Bay and Daphne’s birthday, and the Kennishes have decided to buy each daughter a car. While Bay is excited, Daphne is apprehensive about allowing them to shower her with a gift she knows her mother, Regina, could never afford. After Regina’s been hiding out at Melody’s house for a few days, she hopes to return home to celebrate the girls’ birthdays together with the Kennishes. Meanwhile, Bay and Emmett’s relationship is blossoming, but like most things, has been kept a secret.
As Bay holds her art-show an unexpected guest makes an appearance and, Daphne opens up to Emmett about the feelings she has for him.
Kathryn finds a nurse who may have known that Bay and Daphne were switched. Bay crashes a festival where Guitar Face (Toby, Wilke, and Emmett) is playing because she hears that Daphne is there; Emmett doesn't want a jealous girlfriend. Bay's friend and Wilke's ex-girlfriend Simone flirts with Toby.
Simone dares Daphne to go over and kiss a guy; the guy is up for it, but his girlfriend is not as excited about this.
As Angelo makes Regina a business offer, Daphne finally confronts him about the reason he left. Meanwhile, Melody's opinion of Bay and Emmett's relationship doesn't improve when he gets in trouble. And the Kennish's entire case against the hospital is put in jeopardy when they learn some new disheartening information about their lawyer.
John and Kathryn meet with several new possible lawyers concerning their legal issues with the hospital. Also, Kathryn's writing a memoir about her experiences.
Angelo attends a dinner at the Kennishs' home; Emmett goes to live with his father where a nervous Bay prepares to meet Emmett's father and is high on nerves due to her disastrous relationship with Melody. Meanwhile, Wilke has some shocking news for Daphne and a woman who has a history with John shows up. Also during one of the aired commercials it is shown that Bay and Emmett might take their relationship to the physical level. It shows Emmett asking if Bay wants to quote "stay over, stay over."
We meet Monica, a teenage Latina who Daphne knew from her old neighborhood. She's on a track team that practices at Buckner Hall. Monica and Simone clash when Simone suspects Monica stole her watch.
One of Regina's clients owns an art gallery and Regina gets him to look at Emmett's photos.
Regina has a display at an art gallery. Daphne and Wilke lead a tour at Buckner Hall for several boosters. She's supposed to be talking up the school, but her focus goes elsewhere.
Kathryn and her lawyer meet with Angelo's lawyer, who reveals the hospital plans to argue that Regina switched the babies on purpose. Regina meets with a mother whose daughter lost her hearing. Daphne is playing basketball at the Carlton School for the Deaf; she doesn't get along with a boy named Theo.
Bay becomes involved with Emmet's custody battle. Elsewhere, Daphne's two schools play each other in a basketball game
Daphne and Bay plan the perfect birthday for Emmett - an ASL zombie movie shoot with their friends and family. While Emmett is excited about the event, he's also torn up inside about what happened with Simone and how it will hurt Bay. Simone wants to keep what happened between her and Emmett a secret, but someone finds out and threatens to expose their secret. Meanwhile, Kathyrn is devastated to find out that John has been revealing some secrets of their own and Regina has second thoughts about contributing to Kathyrn's book.
In the winter finale, the Carlton prom gets underway, and Travis tags along with Daphne and Wilke, while Emmett feels the weight of the secret he's keeping from Bay. Elsewhere, Angelo resurfaces; and Kathryn and John's lawyer crosses a line.
Bay returns from a trip abroad with a new boyfriend, but she must face issues from her past concerning Emmett and Angelo. Meanwhile, Daphne seeks employment help from Kathryn; and Regina impulsively makes a big decision.
Regina's actions rock both families. John's baseball record is in danger of being beaten. Daphne and Emmett decide to enter their zombie film in a horror film festival. Emmett has a run-in with Toby. Meanwhile, Bay meets another street artist.
Daphne feels like she's a minute away from being fired after she causes a major accident at the restaurant. But things take a turn when her new boss, handsome Chef Jeff, asks her to stay late one night. Meanwhile, Bay uses Angelo as her excuse to get around John's rules. And Kathryn is upset when Regina gets all of the attention in her interview for the new book.
Daphne tries to ignite a spark between Robin and Emmett at the bike show held at John's car-wash. Meanwhile, John is livid when the car wash is tagged, and Kathryn tricks Toby into getting out of the house.
Bay and Zarra search for a tagger who's been painting over their street art. Meanwhile, Daphne gets mixed signals from Chef Jeff.
Kathryn and John are concerned about Bay's friendship with Zarra so they invite Bay's ex-boyfriend Alex and his parents over for dinner. But during the meal, Zarra calls and begs Bay to come rescue her from a sticky situation. Meanwhile, Scuba pressures Daphne into lying to Chef Jeff for him. Plus, Toby bonds with Nikki, and Regina tries to reconnect with Patrick.
The lawsuit against the hospital comes to a head as Angelo returns in time for the beginning of the trial. Meanwhile, Bay scrambles to return the money she "borrowed" from John to help Zarra. Daphne and Jeff struggle in their relationship; and Emmett, Nikki and Toby form a new band.
The Kennish and Vasquez families are starting to fall apart. Daphne and Jeff's relationship is exposed, causing them major problems. Bay and Zarra take off without telling anyone. Meanwhile, the trial reaches a shocking conclusion.