Daphne and Bay are so enthralled with China that they stay longer than anticipated, but after 10 months, they get an emergency call and drop everything to return home. Once there, Daphne tries to integrate herself back into campus life but finds that things have changed without her. Bay is mixed up about her feelings towards Emmett who is struggling with his own problems. Meanwhile, Kathryn and John quarrel over her job and Regina feels guilty about a secret tryst.
After a photo of Daphne and Mingo dressed up as their favorite singers at a college costume party goes viral, the pair find themselves caught up in a controversy that escalates into a discussion of race relations and free speech. Bay seeks a job at the tattoo parlor in town. Kathryn and John court a new shortstop for the UMKC baseball team, while Regina and Luca work on a class project together.
Returning from London for a visit, Toby and Lily reveal their plans to get married in the Kennish backyard. But a fight before the wedding may tear them apart before they can say "I do". Regina must decide whether to reveal her relationship with Luca to the family. When she least expects it, Bay runs into Tank again.
After Daphne and Sharee witness a threat to the Black Student Union, Daphne attempts to make sense of the escalating racial tensions on campus.
With tensions running at an all-time high, the Black Student Union takes a stand against the school administration until their demands are heard.
Daphne takes a volunteer job at a clinic for extra credit and comes face-to-face with her old mentor, Dr. Jackson. While eager to mend fences with him, she grows alarmed when it becomes obvious he's having trouble properly treating his patients.
In the series 100th episode, a mysterious young woman has Bay and Daphne flooded with memories of their deceased father Angelo, and they must decide if they should let her into their lives. Toby is caught between his mother's wishes to baptize his son Carlton and his wife's feelings about faith. Melody asks her sons to make amends so the family can be together for her birthday, but it might be too late.
Needing to pay their electric bill, Bay and Daphne throw a "lights on" party at their apartment above the Cracked Mug but things go awry when Toby overhears two students making disability jokes. Toby and Bay's high school frenemy Simone turns up looking glamorous and successful. Meanwhile, as Daphne and Chris get to know each other better, she starts to suspect that he's hiding a big secret. Kathryn and Regina do some old-school snooping on Luca after Regina sees a questionable text on his phone.
Travis and Bay have dinner with his birth mom, but the reunion dredges up painful memories of his childhood assault. Daphne contemplates helping Chris cheat on a test. Regina gets paid an unexpected visit.
Kathryn becomes nostalgic when she realizes that it's been five years since the switch was discovered and the two families started living together. As she searches for memories, Kathryn discovers a long buried family secret - stretching all the way back to the switch - that changes everything. Daphne competes against Mingo for a six-week paid internship in sports medicine. Bay is celebrated for her tattoo work in a magazine spread, but her struggle to prove herself as an artist to John threatens to destroy their relationship. Toby meets Amelia (guest star Lauren Potter, "Glee"), a young woman with Down Syndrome who changes his perception about his son's future. Melody, Emmett and Travis make some major decisions about their lives, and Regina takes a chance on love.