Andi's world turns upside down when her older sister, Bex, returns home on her 13th birthday and reveals a family secret.

Andi invites Amber over for a sleepover. Buffy is frustrated when the basketball team captain TJ excludes her from gameplay.

When Andi and Celia spend more time together, Bex feels jealous; Buffy agrees to tutor TJ if he agrees to pass her the ball on the court.

Andi gets in over her head when she attends a high school party with Amber, causing Bowie's plans for a romantic outing with Bex to go awry; Cyrus tries to mend a longtime rift between Jonah and T.J.

Andi lends a hand when Buffy's coaching skills are tested at the school's first girls' basketball game; Amber helps Cyrus create a dance routine; Libby is disappointed that Jonah hasn't learned sign language.