|Season 1, Episode 10|
|Air date||September 1, 2015|
|Written by||Jaime Paglia|
|Directed by||Jamie Travis|
I Know What You Did Last Summer
Emma's search for answers finally ends when the killer is unmasked.
Following the reveal of a bloodied Clark Hudson tied upon a tree with rope, Emma Duval sends Piper Shaw to the police department while Emma calls Kieran Wilcox. Maggie Duval investigates the death of a police officer handcuffed to a cell and while doing so, she finds a carving of a heart inside his throat. The carving was one of many gifts that Brandon James sent to her two decades earlier.
When Maggie and Emma attempt to get Clark untied from the tree, Maggie accidentally leaks out Clark's internal organs, killing him. Meanwhile, at Brooke Maddox's Halloween party, party attendee Grayson Pfeiffer is mysteriously murdered in the washroom. Everyone escapes in fear except for Audrey Jensen, who went to investigate the death. When Audrey finds Grayson's body the killer appears and grabs her. When Audrey asks the killer "What are you waiting for?" the killer apparently stabs her in the neck. Maddox returns with two wine bottles upon realizing everyone was gone. Seth Branson, now escaped attempts to get in the Maddox household, but is unable to due to Brooke locking the doors. When he asks Brooke to let him in, Brooke refuses believing that he is the killer, despite his attempts to explain that he was framed. A brief blackout suddenly appears and when the power comes back on, Branson is gone and The Killer is there. The Killer breaks into the house and gives chase to Brooke who tries to hide in a freezer but The Killer sees her shut the door. The Killer locks her inside and tries to stab her through the doors of the freezer but is only able to inflict minor injuries. Unable to kill Brooke, The Killer turns on the freeze and leaves Brooke to freeze to death inside.
Emma and Noah Foster arrive at the Brooke household and find Piper's glasses and phone in a puddle of blood then assuming the killer had beaten her to death with a car door. Kieran, armed with his gun, arrives only to be saddened by his father's death. The trio unlock Brooke from the freezer and manage to find Audrey, whom was only slashed on the shoulder. Later, The Killer tells Emma that she has kidnapped her mother, Maggie Duval. In order to get her back, she must meet him at Wren Lake, alone, threatening to kill Maggie and more people if she does not comply. Emma does so and at the lake, Emma finds Maggie tied up in a chair at the docks and rushes to her. But before she can free Maggie, the killer appears and Emma demands to know his identity. Seeing no further reason to conceal the truth anymore, The Killer slowly reaches up for the mask and removes it. The Killer is finally revealed to have been always been Piper Shaw (Somehow, she faked her death), shocking both Emma and Maggie. Piper explains that she had been behind all of this from day one. She reveals that her real father is Brandon James; she was the baby that Maggie had sent away for adoption and never gotten to know. Upon finding out about this, she has always viewed Maggie as the true "monster" for her part in getting Brandon killed. She was also jealous of how she was sent away for adoption while Emma had the perfect life. She vowed to make them both pay for it all. Emma asks why she had killed her friends since they didn't have anything to do with Brandon's death. She replies that all that was meant to do was make Emma suffer which she had enjoyed greatly, disgusting Emma.
Piper goes on to explain that Branson is tied up in the trunk of her car, whom she intends to frame for the murders. Piper continues to say that she will make up a story that Branson had killed Emma and Maggie but not before Emma fatally stabs Branson. Eventually, Emma gets angered enough to attempt to attack Piper with a knife she had hidden behind her back, only to be viciously slashed across the stomach (Piper knew she had the knife all along), critically injuring her. Piper continues to rant on how Emma is so "predictable" and that she will kill Emma in front of Maggie and then leave Maggie to die after stabbing her. Maggie manages to free herself from her binds due to Emma's efforts and tackle Piper to the floor but is in turn stabbed in the stomach. Piper then goes on to attack Emma, repeatedly attempting to slash her some more. Soon enough, Piper injuries Emma further and holds her at knifepoint.
Piper tells Emma that she has one more surprise to share and that she'll "never see it coming" but before she can say what it is, she is shot in the chest by Audrey with Kieran's gun, causing Piper to fall into the lake. Audrey explains that she had gotten her hands on the gun when Kieran handed it to Noah but Audrey took it from him as she knew how to use it. She saw Emma running to the woods and followed her she then found them all at the dock. She then comments "bitch talks too much". Piper survives and begins to climb back up the dock for one last attempt to kill them. Emma notices this and she shoots Piper in the head before she can attack, finally killing her and ending the killings.
The following morning, Maggie is sent to the hospital while it is revealed to the world that Shaw was the murderer and Audrey saved Emma from near death. Audrey had letters from Shaw talking about something, implying that Audrey was killing people with her (likely the secret that Piper tried to tell Emma). However, she burns them, now redeeming herself and covering up her "involvement".
- Willa Fitzgerald as Emma Duval
- Bex Taylor-Klaus as Audrey Jensen
- John Karna as Noah Foster
- Amadeus Serafini as Kieran Wilcox
- Carlson Young as Brooke Maddox
- Jason Wiles as Sheriff Clark Hudson
- Tracy Middendorf as Maggie Duval
- Amelia Rose Blaire as Piper Shaw
- Bobby Campo as Seth Branson
- Tom Maden as Jake Fitzgerald
- Lindsay Musil as Ava Miller
- Bryce Romero as Grayson Pfeiffer
- Ryan Broussard as Deputy Roberts
- Mike Vaughn as Killer(Voice)
- Clark Hudson - Stomach cut open by Kieran Wilcox; Accidentally killed by Maggie Duval
- Grayson Pfeiffer - Throat Slit (Off-Screen) by Piper Shaw
- Piper Shaw - Shot in the chest and head by Emma Duval and Audrey Jensen
- The episode was watched live by 0.76 million viewers.
- The Killer reveals herself as Piper Shaw.
- Unlike Tatum from Scream, Brooke managed to survive the Lakewood massacre with minor injuries.
- Jake confessed that he's the one who was spying on Brooke on her webcam.
- It is revealed that Piper Shaw is Brandon James and Maggie Duval's daughter, and Emma's half-sister.
- Piper Shaw tortured Emma because she had the perfect life while she was abandoned by her mother, Maggie Duval, whom she gave her up for adoption. This is Roman's reason to kill Sidney in Scream 3.
- Piper Shaw revealed that she killed Emma's friends to watch her suffer.
- Emma Duval shot and killed Piper in the forehead just like Sidney did to Billy Loomis in Scream, and Mrs. Loomis in Scream 2.
- There was a chase scene at Brooke's house in this episode. Brooke was attacked by the killer before she was saved by her friends.
- Seth Branson was found innocent and was released from custody as well as Quinn Maddox.
- In the episode, Emma received calls from the killer.
- This episode marked the deaths of Sheriff Clark Hudson, Grayson Pfeiffer as well as the Lakewood slasher, Piper Shaw.
- The way that Piper Shaw died at Wren Lake parallels the way her father, Brandon James, died.
- Although they couldn't find Piper Shaw's body at the end of the episode, show runner, Jill E. Blotevogel confirmed that Piper is dead. 
- This episode contains multiple references to the Scream films.
- Jake's quote, "Landlines? What is this 1996?" is a reference to the year the first film was released. Ironically, they actually appear in the film.
- Grayson pranking Brooke while wearing the Brandon James mask is a reference to the first film as well, when two high school students prank Sidney wearing the Father Death mask.
- The scene where Seth asks Brooke to open the door before being attacked by the Lakewood Slasher resembles a scene in Scream 4, where the same thing happens with Charlie and Kirby.
- Noah (again) uses the line "I'll be right back", only saying the opposite.
- The scenario in which the killer comes back to life is used again, a reference to all the films.
- The episode was dubbed “#WhoIsTheKiller" by MTV across social media.
- This episode marked the final episode of Season 1.
- Filming for this episode wrapped up on July 19, 2015. Source
- A day prior to airing, the director of the Scream movies, Wes Craven passed away. Subsequently, the episode is dedicated in his memory.
- Audrey was revealed to have been working with Piper and in the final scenes, burns letters of evidence linking her to Piper. Jill E. Blotevogel also confirmed that it was Audrey who attacked Will Belmont and Piper in the abandoned car dealership. 
- Jake Miller – “Shake It”
Source at Brooke’s party as she wonders why real real friends aren’t around and why she can’t get a hold of Emma.
- Skully Boyz – “Lifetime”
Source at Brooke’s party as Brooke gets scared by Grayson. Brooke and Audrey commiserate.
- Darion Ja’Von – “Nights Like This”
Source at Brooke’s party as Jake makes out with Ava. Brooke and Audrey bond. Brooke makes Jake jealous.
- Chris Arena ft. I O N A – “Memory”
Source at Brooke’s party as Ava looks for Jake and finds Grayson dead on the floor.
- THRILLERS – “Can’t Get Enough”
Source at Brooke’s party as Brooke comes back to a totally empty party and thinks everyone ditched her.
- Pawws – “Time To Say Goodbye”
Source at Brooke’s party as Emma, Noah, and Kieran search for Brooke, Audrey, Jake, and Piper.
- Fort Lean – “Quiet Day”
Montage of people leaving in ambulances, a sense of relief in the town, and the discovery that the killer didn’t work alone.
Behind the Scenes
|Season 1||Pilot • Hello, Emma • Wanna Play a Game? • Aftermath • Exposed • Betrayed • In The Trenches • Ghosts • The Dance • Revelations|
|Season 2||I Know What You Did Last Summer • Psycho • Vacancy • Happy Birthday to Me • Dawn of the Dead • Jeepers Creepers • Let The Right One In • Village of the Damned • The Orphanage • The Vanishing • Heavenly Creatures • When a Stranger Calls • Halloween • Halloween II|
|Season 3||The Deadfast Club • Devil's Night • The Man Behind the Mask • Ports in the Storm • Blindspots • Endgame|