The girls examine the video "A" left for them that illuminates what looks to be the final moments of Alison's life by the Kissing Rock the night she disappeared; right after Ian's cameo on the video, he surprises them in person as he tries to grab a late night snack from the Hastings kitchen - as it's become more clear than ever that danger is always just around the corner in Rosewood.
The girls grow increasingly overwhelmed with the possibility of who (or whom) "A" could be, and whether he/she/they will be making an appearance at the Rosewood High Dance-A-Thon they've all been preparing for. They are even more overwhelmed when they discover Spencer's laptop is missing.
Hanna, meanwhile, is eager for a job to help support the Marin's financial strife. And Aria's babysitter Simone makes a surprise return to Rosewood - a blonde, beautiful, and intelligent - she was Aria's role model and "big sister" growing up, a now-published author who hits it off immediately with Ezra, which only complicates an already complicated relationship.
Emily enlists the help of new kid Caleb, a good-looking bad boy with a tech cred, to help unlock her phone to get through to Maya at True North, the rehab center where she's being housed. Meanwhile, Ian is asked to chaperone the Dance, and the girls are convinced that he has Spencer's missing laptop in tow.
At the Dance-A-Thon, Hanna must contend with constant instructions from "A" throughout the dance in an effort to regain some of her mother's money. "A" makes her dance with Lucas and then break his heart. Meanwhile, after a terse call with Maya, Emily finds herself drinking at the dance and nearly causes an accusatory scene with Ian.
When the girls return from the dance, they find Spencer's computer waiting for her on the counter with a picture and note from "A" - a photo of Alison the night she disappeared, in Spencer's backyard.