Callie admits her past relationship with Brandon to her moms. But before Stef and Lena can even process the information, the school goes into a “Code Blue” lockdown when it’s discovered Mariana’s boyfriend Nick showed up with his father’s gun after seeing her kiss her ex-boyfriend Mat.

Lena is excited that her family is coming together to throw her a 70s-themed 40th birthday party. But, when Lena’s mom Dana shares her suspicions about Stewart’s behavior, it threatens to put a damper on the festivities. Convinced her former foster brother Kyle has been wrongly convicted of murder, Callie and Aaron try to track down a witness in the case. Mariana and her female STEAM club teammates compete for an invite to the Regional Robotics Competition. Meanwhile, Jude is hurt to discover that Connor came to town and didn’t tell him, and Brandon considers drastic measures to make extra money.

Lena is shocked by the news that her dad has been hiding something that directly puts them all in jeopardy. Additionally, she uncovers a major secret that Brandon has been keeping. Mariana continues to be pressured by Nick and must deal with direct opposition from the male members on her STEAM team. Meanwhile, Jesus grows resentful of Emma’s behavior, and Jude discovers Noah has a medical marijuana card.

Mariana and Jesus compete in the First Robotics Southern California Regionals, but when Mariana gets too competitive under the stress, Lena grows alarmed. Callie gets a warning from the police to stop harassing Patrick Molloy. Brandon practices for his fast-approaching Julliard audition.

Callie actively helps to make Ximena’s fight visible. Meanwhile, Brandon and Grace struggle to be intimate knowing her diagnosis and Mariana is suddenly courted by multiple suitors.

Callie and her friends support Ximena in a big way at a conservative anti-immigration rally and get a lot of buzz for Ximena’s plight. Meanwhile, an unlikely source offers a key piece of evidence that may help save Anchor Beach from going private and the family celebrates Stef’s birthday.

Brandon and Grace plan the ultimate senior prank which ends up going a little too far. Mariana and Mat make a huge decision about the future of their relationship.

Stef’s mom comes to visit and helps Stef cope with a tough time. Meanwhile, Callie and Jude grapple with the memory of their biological mother.

Callie speaks on a panel about Ximena’s struggle and realizes she may have a passion for something other than art. Meanwhile, Mariana is torn between two suitors.