This episode opens with Dexter walking along the beach and observing "I find people around me are all making some kind of connection, like friendship or romance but human bonds always lead to messy complications; commitment, sharing, driving people to the airport, besides if I let someone get that close, they'd see who I really am and I can't let that happen, so time to put on my mask." But this is not just a walk on the beach; Dexter is arriving to a crime scene, where Angel is waiting, along with a severed hand, placed on a lawn chair.
Because there is blood with the hand (on a towel on the chair) and the hand belongs to a male, Dexter isn't sure if this is another piece of work by the Ice Truck Killer (ITK) or not. The killer also left behind a Polaroid picture of the crime scene in a pail, next to the hand. As Dexter absorbs that, he suddenly flashes back to his childhood and a day at that same beach, in that exact location. In this flashback we also get to see Dexter's Mom for the first time. Dexter gets talked into smiling for the picture they are taking, because Harry tells him it is how he can fit in.
Dexter races home from the beach to check his photo album and confirm his memory is correct. It was that beach, it was that location and this severed hand is from the ITK. Dexter calls him "my new friend, the Ice Truck Killer."
Back at the police station, the captain arrives with news that fingerprints from the hand that was found belong to Tony Tucci, the security guard from the ice rink where the last body was found. Lt. LaGuerta had gone on television to name Tony as the ITK and now the captain orders her to visit Tony's mother to apologize for her mistake.
Sgt. Doakes, Deb and Angel are all back at the beach, along with other police, trying to find any additional clues and talk to any potential witnesses. At first both Deb and Angel would rather talk with Doakes about the hot water the Lt. is in, but Doakes is in no mood for conversation, having spotted Guerrero's men on the perimeter of the crime scene.
Despite her trepidation at having to deliver a mea culpa to Mrs. Tucci, Lt. LaGuerta finds her to be not as much concerned with laying fault on the police department as she is in having them find the rest of her son. In our first episode we learn that Dexter killed a neighbor's dog because its constant barking and whining was disturbing his sick mother. In this episode it is the dog of Rita's neighbor that is making all the fuss. When Dexter goes to talk to the owner, he finds the dog belongs to the boyfriend of the woman who lives next door. Apparently he left and didn't take his dog and the lady shows she has no compassion for Dexter's polite request to quiet the dog, shutting the door in his face. As he walks away, remembering his youth, Dexter says "I could make things so much easier for Rita" and then he pauses, then says "but that would be wrong."
Dexter gives us his take on Halloween "I love Halloween, the one time of year when everyone wears a mask, not just me." He goes on to say that "People think its fun to pretend you're a monster, me I spend my life pretending I'm not" reminding us just how different he is from those around him.
Another crime scene reveals what Dexter calls "another photo from my family album, he's recreating my past with Tony Tucci's body parts." This time it is a severed foot, on a bench, in a soccer shoe, next to a soccer ball. Dexter tells Doakes (who sees Guerrero's men on the perimeter of this crime scene) that the presence of blood with these body parts is some sort of message on the part of the ITK, but claims to not yet know what that message is. When Doakes asks who the message is for, Dexter also feigns innocence, but as we know, the messages are definitely for him.
Dexter knows exactly what is going on and the messages being sent, he tells us "He knows, he's not corrupting the happy Hallmark images of my youth; he's revealing the ugly truth behind them." In a flashback to a soccer field at the new crime scene (which is now the office park where the bench is), we see Dexter as a youth, being chided by Harry for his involvement in teasing a teammate.
Deb is assigned the task of going through many surveillance tapes pulled from cameras around the crime scenes. The Lt. is hoping that on at least one of them there is a picture of the ITK. Meanwhile Doakes confronts Kara's brother about the reality of her marriage and accuses him of "backing the wrong cop." From the expression on his face, we can tell that Doakes' words left an impression on him.
Rita's attempts to talk to her neighbor about the noisy dog, that has now completely exhausted her and her kids, goes about as well as Dexter's. Rita is taunted by her neighbor and is left with the door being abruptly shut in her face too.
Dexter makes a startling discovery while making small talk with Angel at the station. From the identical condition and blood flow of the two severed body parts (found a day apart) Dexter is able to discern that Tony Tucci is still alive. Dexter and Angel have also noticed that the body parts have been dropped off each day at around 7am, leading them to believe that at 7am the following day, they will receive the next part of Tony Tucci. While Maria LaGuerta informs Tony's mom, the cops meet to try and ascertain where the next body part will be dropped off.
Deb is tired of being stuck watching the video tapes and pleads with Dexter on the phone to help her find where the next body part will appear. Dexter is just as confused as everyone until Deb tells him to pick a spot, any spot, his favorite spot. Without letting on to the fact that she has helped him get onto something, Dexter does pick his favorite spot; the garbage dump.
The garbage dump is now condominiums and Dexter arrives to find nothing but a sleeping man. While standing there trying to figure it out, he receives a call from dispatch to go to a local pumpkin patch. In a flashback to that location, we see Dexter, Deb and Harry on a hay ride. It is at this pumpkin patch, in a cart very much like the one they were riding in as kids, that the police now find Tony Tucci's ankle and leg. This leads Dexter to think that if Tony is still alive, he won't be for long.
We almost think that Rita's neighbor's dog is dead and gone, but we quickly find that she has taken him to a family with children who will love and care for it. Later she shows up unannounced at Dexter's ready to have some adult fun. While Dexter is learning to enjoy (or at least tolerate) this new side of his relationship, we see a new side of Angel and his relationship with his wife of 10 years, Nina. After being shot down twice for his choice of gifts for their 10 year anniversary by Dexter, Angel is filled with confidence that his latest choice (and his dapper look) will be sure to go over well by Deb. Unfortunately when he arrives home, we learn that for the last 3 months, Angel's marriage has been very rocky.
Rita spots some of the photos from Dexter's youth on his desk as she is getting ready to leave following a somewhat hilarious scene of "unexpected" fun. Dexter, it turns out, can enjoy some things, and Rita has found one of them. In observing how it seems that Harry is always watching over Dexter (from the photos), Dexter sees a happy face on the back of one photo. He knows it was placed there by the ITK and it is of the hospital where Harry's father had worked for years. It is also one of the last photos of Harry and Dexter together. It is obvious that Harry is quite ill (and Dexter much older) in this flashback. Harry will soon die.
Dexter heads out to where the hospital used to be. Before he arrives at the building, we flash over to Sgt. Doakes arriving home, but being knocked unconscious by Guerrero's men and taken away with a hood over his head. As Dexter arrives at the building he observes "hospital's shut down now, abandoned for years, but tonight, its visiting hours again." We flash back and forth between Dexter at the hospital and Doakes with Guerrero. Guerrero's men have delivered Doakes to him and it seems that Doakes will be killed. Just as Guerrero raises his gun to shoot him, he himself is shot by what turns out to be Officer McNamara (Kara's brother). It seems this was his plan all along, to use Doakes as bait to get to Guerrero. As it seems the plan has worked, and as Guerrero is taken into custody, McNamara tells Doakes that his sister can rest in peace and the two men are even now.
Back at the hospital, Dexter hears cries for help. As he goes to investigate, he finds Tony Tucci, very badly hurt, cut, begging for death. With all the tools around him to do the job, Dexter feels that the ITK has left him a gift-wrapped package, but the problem is that the "Code of Harry" will not allow Dexter to finish what the ITK has started. A sudden breaking of a window and the flash of a camera, tell us all that the ITK is there and watching. Dexter races up the stairs to find the Polaroid camera (with the freshly taken photo still there).
He gets a message to Deb to come to the hospital, and she is able to take the credit for finding Tony Tucci alive. A collage of scenes at the end of the episode shows all the key players where they are and what they are doing. Dexter's voice tells us that "everyone hides who they are at least some of the time, sometimes you bury that part of yourself so deeply that you have to be reminded that its there at all, and sometimes you just want to forget who you are altogether."
This Halloween episode of Dexter ends with him observing that "I'm not the monster he (the Ice Truck Killer) wants me to be, so I'm neither man nor beast, I'm something new entirely, with my own set of rules, I'm Dexter."