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.

When Jesus’s birth father, Gabe, doesn’t show up to work on Stef and Lena’s garage, Jesus takes on the job himself and gets injured in the process. An exhausted Mariana, deep into her robotics STEAM project, takes Jesus’ ADHD medicine for a boost. Callie and AJ find themselves in an awkward situation when Mike and Brandon unexpectedly come home early. Meanwhile, Stef lets Mike know that Brandon gave his hand injury settlement money to Cortney.

The Fosters kids attend a party at the Derby warehouse, but things escalate quickly when the cops show up. Lena struggles when Stef starts to become obsessed with an ongoing case at work, meanwhile Brandon’s relationship with Grace is put into jeopardy with Courtney back in his life.

Callie is torn with turning over a new leaf or supporting a cause that means a lot to her, while Jude and Taylor begin making gaming videos that earn them unwanted notoriety. Stef makes major headway in her case.