In the Season 4 finale, Callie must decide to take a plea deal and go to jail for three years or go to trial and risk an even longer sentence. Meanwhile, Stef and Mike ramp up their investigation into the murder; Lena confronts Drew about his campaign; Mariana rallies her fellow students to protest; and Jesus starts to put together the pieces about Emma.
Everyone in the Adams Foster household has a secret, but they all start spilling out. Meanwhile, Robert's attorneys propose a strategy that Callie opposes; Monte and Lena join forces to stop Drew's underhanded dealings; Stef works to bust Diamond's pimp; and Jesus asks Gabe to keep a secret from his moms.
Lena is at her wit's end when everyone comes to her to handle all their crises and Stef is never around to help. Elsewhere, Aaron invites Callie on a road trip to visit his parents; and Jude resorts to bullying tactics of his own after being fed up with being bullied at school.
Stef starts a new assignment in human trafficking and meets a teenage girl who turns tricks on the streets. Elsewhere, Lena deals with repercussions of holding an off-campus LGBTQ sex ed class; and Callie's pursuit of justice impacts her relationship with AJ.
Sharon and Will announce that they are engaged. Meanwhile, Stef learns that her mom has second thoughts about getting married; Emma writes Jesus an honest letter; and Jude is teased at school when Lena holds an LGBTQ-friendly sex-ed class for students.
Jesus grows suspicious of Brandon and Emma's relationship; Jude uses a dating app for adults to learn about LGBT sex after discovering the topic isn't covered in sex ed; and Callie's senior project is criticized by the school's administration.
Stef removes the kids' bedroom doors after being fed up with their secrets; and Mariana begins seeing a therapist again. Meanwhile, Jesus starts physical therapy; and Callie's biological father enlists his high-paid attorneys to take on her case.
Callie rejects a proposition from a guard in juvenile hall, making an enemy in the process. Meanwhile, Callie's father is angry at Stef and Lena; Brandon puts Mariana in a bad position; Jude gets another chance with Noah; and Mike makes big decisions.
Jesus has a nightmare that he's unable to save Mariana while he's unconscious at the hospital. Meanwhile, Stef and Lena learn that Callie is in legal trouble; Mariana seeks comfort from Mat; and Brandon tries to hold the family together.
Jesus is knocked out and rushed to the hospital, where he fights for his life. Elsewhere, Callie's put in danger after taking a ride with Troy; and Mariana feels guilty that her actions led to Jesus' condition.
Callie and the family set up a Justice for Jack booth at a music festival in hopes of stopping Justine's foster-care bill, but Callie's advocation for both Kyle and Jack puts her in danger. Meanwhile, tensions between AJ and Aaron escalate; and Mariana flees from the festival after seeing Nick, leading the family to frantically search for her.
Brandon travels to New York for his Juilliard audition, where he meets a girl who forces him to take a hard look at his relationship with Cortney; Lena and Stef shock the family with an announcement; and Callie's friendship with Aaron leads to trouble with AJ.
Mariana and Jesus compete in the First Robotics Southern California Regionals. Meanwhile, Lena becomes concerned that Mariana has grown too competitive from the stress; the police warn Callie to stop harassing Patrick Molloy; and Brandon practices for his upcoming Juilliard audition.
Jesus sustains an injury after he tries to cover for his father who didn't show up to work. Meanwhile, Mariana takes Jesus' ADHD medication after feeling drained; Callie and AJ are caught in an awkward situation when Mike and Brandon arrive home early; and Stef tells Mike that Brandon gave his settlement money to Cortney.
Lena and Stef are shocked by a secret Lena's father has been hiding that could jeopardize the entire family. Meanwhile, Lena confronts Brandon about the money he gave to Cortney; Mariana must deal with the male members of her STEAM team; Jesus begins to resent Emma; and Jude discovers Noah has a medical-marijuana card.
The family plans a '70s-themed birthday bash for Lena, but Lena's mother's concerns about Stuart threaten to ruin the party. Meanwhile, Callie and Aaron try to prove Kyle's innocence; Mariana's STEAM club vie for an invitation to a robotics competition; Jude's upset when he learns Cameron visited town without seeing him; and Brandon considers drastic measures to earn extra cash.
Brandon throws a party at his and Cortney's place, not realizing the complications of living with a mom and young child. Meanwhile, Cortney gets custody papers from her ex; and Callie uncovers some disturbing info as she works on her senior project.
Callie gets suspended after she reacts inappropriately to some taunting, but things start looking up for her when she meets a young law student. Meanwhile, Mariana's classmates fault her for Nick's actions; and Jude is invited to Taylor's youth group.
The Adams Foster household's on lockdown in their own home following the crisis at school; and Callie and Brandon anxiously wait for their mothers to address their behavior in Idyllwild. Meanwhile, Stef's furious when she discovers Brandon snuck out to help Cortney move.
In the fourth-season premiere, Nick takes a gun to school after seeing Mariana kiss Mat, forcing the school to go on lockdown. Meanwhile, Stef and Lena struggle to process Callie's confession about Brandon amidst the crisis.