Warning: This article contains SPOILERS for Dexter: New Blood episode 4.

The ending of Dexter: New Blood episode 4, “‘H’ is For Hero,” answers several of the season’s mysteries, while setting up Harrison's trajectory with familiar ominous smile from Dexter. New Blood's timeline picks up nearly a decade after the original series, following the titular serial killer as he lives in the fictional Iron Lake, New York under the alias Jim Lindsay. After the return of his long-lost son Harrison Morgan, and the discovery of a looming serial killer in his adopted home, Dexter returns to feeding the murderous urges of his Dark Passenger.

Dexter: New Blood episode 4, “‘H’ is For Hero,” kicks off with Dexter receiving an alert that Iron Lake High School is on lockdown. He arrives to discover that Harrison is injured, having supposedly been stabbed by Ethan, a student that planned on enacting a mass shooting at school. Dexter realizes several inconsistencies in Harrison’s story, soon finding out that Harrison lied—he had actually cut Ethan in the leg to “know how it feels” before stabbing himself as a cover-up. Confirming that Harrison has a Dark Passenger like he suspected, Dexter finds a straight razor hidden in his flashlight; the same blade The Trinity Killer used to murder Harrison's mother Rita. At this discovery, Dexter puts the blade to his lip and smiles before New Blood’s episode 4 cuts to black.

Related: Dexter: New Blood Episode 3 Ending Makes Matt's Death Darker

Elsewhere in New Blood’s chaotic episode, Angela is teaming up with true crime podcaster Molly Park to discover the whereabouts of Iron Lake’s many missing persons. All the while, one of the show's biggest mysteries is answered, as Kurt Caldwell is confirmed to be Iron Lake’s serial killer. The ending of New Blood episode 4 sets up much of Dexter’s season, stemming from Kurt’s mysterious actions, Harrison’s Dark Passenger manifesting, and Dexter’s malicious, telling smile in the episode's final seconds.

Kurt's Serial Killer Reveal Answers New Blood's Matt Mystery

After three episodes of hinting at a mysterious masked murderer, “‘H’ is For Hero” finally confirms that Kurt Caldwell is New Blood’s serial killer. He’s shown taking a traveler back to his secret cabin in the woods, where he will soon place her in the room that he used to trap his most recent victim. While the revelation of Kurt being New Blood’s serial killer confirms him to be Dexter’s biggest villain to date, it also answers the mystery surrounding why he lied about his son Matt being alive.

Dexter murdered Matt Caldwell in New Blood episode 1 after discovering he was responsible for the deaths of five people, having just burned his remains at the end of episode 3. After finding a drunken Kurt Caldwell outside of Iron Lake’s tavern, Kurt tells Dexter that Matt is alive, having just FaceTimed him. Considering Dexter murdered him and his ashes were falling on them as they spoke, Dexter was extremely curious as to why Kurt would lie about Matt. Now that Dexter: New Blood has confirmed Kurt is the serial killer, it can be pieced together that the reason for the lie was to stop the police from snooping around his cabin and burial ground.

Angela revealed that Iron Lake’s police were going to start looking around the caves and alternate, isolated grids in the woods, which would have led them to the cabin where Kurt holds and murders his victims. By telling them that Matt is actually alive and simply skipped town, Kurt is able to avoid Iron Lake’s police looking too far into his activities.

Related: Dexter: Why Didn’t Harrison Find Astor & Cody In New Blood?

Harrison’s Dark Passenger Explained

Another major reveal from Dexter: New Blood episode 4 is that Harrison is confirmed to have a Dark Passenger, having developed an urge to kill after the death of his mother, Rita in Dexter season 4. Just as Dexter always feared, Harrison was deeply traumatized by being found in a pool of his mother’s blood, which is now manifesting in his violent attacks on others. Harrison appears to be following in Dexter’s footsteps, taking out his dark tendencies on victims who may be deemed as more harmful than himself.

Not only is he beginning to attack other people, his tactic repeats that of The Trinity Killer. When he cuts Ethan, he does so by slicing his femoral artery, which is exactly how Trinity would murder his first round of victims—Rita Morgan included. Harrison is also utilizing a straight razor as his weapon, which is the same blade Dexter's Trinity Killer used. It hasn’t been revealed whether or not Harrison has officially killed anyone yet, but almost fatally cutting Ethan doesn’t seem to be the end of his Dark Passenger’s influence.

Why Dexter Smiles At Finding Harrison’s Razor Blade

Although Dexter Morgan spent most of the original series and the first few episodes of Dexter: New Blood hoping Harrison was “normal” and wouldn’t turn out like him, Dexter actually smiles when realizing he has a Dark Passenger. As New Blood episode 4 pointed out with Deb’s Dark Passenger manifestation, Dexter feels like he can’t be a father to Harrison unless he’s like him. Deep down, Dexter feels that he can only connect to Harrison if he’s just as dark and twisted because he desperately wants to be someone Harrison can look up to.

Now that Dexter has confirmed teenage Harrison Morgan has a Dark Passenger by cutting Ethan with Trinity’s trademark straight razor, he feels that his son is truly his. Although Deb uses far more colorful words to describe their connection, Dexter is glad that Harrison is just as murderously inclined, having inherited his "sick" Dark Passenger. Now, Dexter isn’t alone in the world anymore, and can finally have a real relationship with his son, no matter how twisted that relationship may become.

Related: Dexter New Blood: Harrison Killed Hannah - Theory Explained

New Blood Episode 4 Ending Hints Dexter Will Reveal The Code

New Blood episode 1’s ending revealed that Dexter wanted to protect and teach Harrison like Harry did for himself, and Harrison developing his own Dark Passenger fulfills this prophecy. Now, Dexter will have to truly become Harrison’s Harry, needing to teach him the Code and how to control his murderous urges. Since he knows that Harrison’s Dark Passenger will soon warrant an actual kill, Dexter will feel responsible to teach him how to hone his urges, making him choose only those who deserve it and “fit the code.” Dexter already suspects that Harrison has a minor sense of morality in this case, surmising that he chose to stab Ethan because he wanted to commit a mass murder, thus falling along the lines of the code.

But, in teaching Harrison the Code, Dexter will have to reveal his own serial killer past and present. This will inevitably open up a tumultuous can of worms, thus bringing up a complicated conversation on Dexter murdering The Trinity Killer and how Dexter could be indirectly held responsible for Rita’s death. By telling Harrison that Dexter himself is a serial killer, his son will at least get a real answer on why he abandoned him in Dexter’s original series finale. It’s been theorized that Dexter: New Blood will end with Dexter Morgan’s death, which could possibly stem from him teaching Harrison the code and sacrificing himself to protect his son, or Harrison killing Dexter as a victim for his Dark Passenger.

Next: What Happened To Hannah In Dexter? New Blood Kills Original Show Character