It's 1968 and a group of teens are driving to prom. One of the girls, Ada, is upset that they left a friend behind, but another girl says she was a slut and didn't deserve to come along. Moments later, a cement block comes crashing down onto the car, landing directly on Ada. She's not dead, but she doesn't seem be alive exactly either...
Back in the present, the mayor of Waterbury announces that Heather Peterson has been arrested for Justin's murder and is being investigated for Verna's as well. Sarah is skeptical that Heather is the one behind Verna and Justin's murders, but Dylan tells her she's beginning to sound crazy.
Brenda is visiting Ada at the nursing home when Sonya arrives. She confronts Brenda for not being around more in the past. Brenda storms out and says it's a shame that the block didn't hit Sonya instead. Oof. That's pretty harsh.
A strange man stops by the gallery and he takes an interest in a painting that Sarah made of the Executioner. She's a little freaked out later that night, so the police department sends a cop over to watch the house just to be on the safe side.
Trent reveals that Justin gave him a bad check, and tells Robin he better get him a new one or else. Robin admits he was unaware of most of the business decisions that Justin made. What was Justin up to?
Brenda runs into Sonya's husband, Ronald (also the mayor of Waterbury), and they start to hook up in the back of a bar. However, he makes a comment about how she's still beautiful as she was when she was a teenager, and she gets upset and leaves.
The officer outside Sarah and Dylan's house is not doing a super great job, and while he's busy playing with his tablet, a familiar pair of black gloves reaches through the car window and chokes him. The Executioner!
After receiving a series of creepy phone calls, Sarah calls the number back and hears a ringing inside the house. Just then, the Executioner rushes down the stairs toward her. She manages to escape up the stairs and hides in the closet until the police arrive.
The police officer who was keeping watch is injured but alive. Cam and Vaughn reveal that the calls came from Verna McBride's cell phone, but Vaughn insists it wasn't the Executioner. Sarah has had enough and decides she wants to leave town immediately. Finally!
Sarah goes to say good bye to Robin, and he's still distraught over Justin's death and confused over why the Executioner targeted him. After some prompting from Sarah though, he remembers something...
A family had been kicked off the property where he and Justin built their house, and they later died after using a propane heater as a makeshift furnace and suffocating to death. But Robin doesn't know how Justin could have been responsible for their deaths.
Dylan informs Alison that he and Sarah are leaving town, but Alison convinces him that the Executioner story could make his entire career. Conflicted, Dylan tells Sarah that he wants to stay a little while longer, and Sarah and Brenda pack up the car and leave.
While driving, Brenda suggests that Cam is interested in Sarah, but before they can broach that line of conversation further, a black pickup truck swerves directly in front of them and they go off the side of the road. Brenda pulls a gun out of her purse and shoots at the truck, but it drives away.
The car won't start back up, so Brenda and Sarah start walking back toward the town in case the truck comes back. Sarah says that the Executioner must be targeting her because she tried to kill herself once, but Brenda reveals that she has an even darker secret...
Brenda wasn't riding to prom with Ada that night; she was the one who dropped the block! She had been aiming for Sonya, who had stolen Ronald from her. Brenda was pregnant with Ronald's child at the time, meaning he's Sarah's grandfather. Sarah tells Brenda she should confess to the police, but Brenda says she refuses to go to jail for a mistake.
Robin discovers Justin had been stealing from his clients. In addition, Justin had the land for their house rezoned before it was built, effectively kicking out the family living there because they could no longer afford the taxes. Super shady, Justin...
Brenda splits up from Sarah and tries to find the Executioner in the woods. Unfortunately, he finds her first... and ties her up to a cement block in a boathouse. She insults him, but he just grabs the block and tosses it in the water, dragging Brenda along with it. She can just barely reach the surface... but not enough to get any air... Bye bye Brenda...
Sarah finds Brenda floating in the water and calls an ambulance, but it's too late by that point. Sarah is attended to by Cam's wife, June, who is a paramedic. However, Cam gives Sarah a big hug, which June does not seem to be super thrilled about.
Robin arrives at Trent's cabin, but he doesn't seem to be around. He goes to a shack in the back, where he finds a bunch of creepy taxidermy creations and sharp instruments. He's startled when Trent returns, being creepy as ever with bloodied hands and a dead animal carcass. Robin says he'll come back later.
Heather is released from custody, since she clearly didn't murder Brenda and there's not enough evidence tying her to Justin. She's irritated, but she tells Cam he has a nice glow to him before she leaves.
Sarah tells Sonya about Brenda's confession, but Sonya denies that Ronald could possibly be her grandfather. Denial... not just a river in Egypt.
Sarah visits Tom and says that the punishment for envy is drowning, which makes sense since Brenda was the most jealous person she ever knew. She thinks the Executioner is not after her, since he hasn't killed her after so many opportunities. Tom replies that the Executioner is blinded by the greatest of all sins: pride.