The episode begins with Evan drinking at the bar when the Muirfield guy arrives to meet him. Evan tells him that he found their creature. He says that the creature is hiding in the tunnels. The Muirfield agent is skeptical, but Evan tells him that his intel is solid. The agent hands Evan a panic button and tells him to use it if required. On his way out, Evan punches a guy sitting at the bar. Vincent is at Cat’s place and he is trying to get some laundry done, when Tess arrives. Vincent apologizes for whatever happened in the tunnel. Tess tells him that it is alright and that she is trying to wrap her head around the whole vigilante thing.
Tess and Cat go to the roof and have a chat. Cat explains the dangers involved in trying to protect Vincent. She tells Tess that if she decides to be in on this, her entire life would change. At that moment, Cat receives a call from the precinct. Evan is arrested for punching a guy at the bar. Cat arrives to meet Evan. Evan tells her that he knows about Vincent and also that he is her boyfriend. Cat tries to explain, but Evan tells her that he was only trying to protect her. Cat realizes that something is not right and she asks him what he did. He tells her that he brought her to the precinct on purpose, so that she isn’t around Vincent when Muirfield finds him. Cat rushes to find Vincent. In the tunnel, the Muirfield agents are in position. Vincent senses their presence and manages to escape. Later, Vincent meets Cat in a park.
Cat tells him that Evan tipped Muirfield about his location. She tells him that Evan saw him at her apartment two days ago and e followed him. Cat tells him that she will talk to Evan and convince him that Vincent is not a monster that Evan thinks he is. She also tells Vincent that Evan is in love with her and he did this to protect her. Vincent thinks that it is time for him to have a word with Evan. Cat tells Vincent that he cannot walk into her precinct and talk to Evan. She assures him that she can take care of the situation. Cat arrives at the morgue and sees that Gabe and his men are going through Evan’s things.
She confronts Gabe and Gabe tells her that he knows that she went to meet Evan in the tank. Cat wants to know why he is going through Evan’s stuff. Gabe tells her that he is going through everyone’s things. She then learns that Gabe went through her stuff as well. Gabe tells her that the warehouse blowing up just when the team reached there seems more than a coincidence. He suspects that there is a mole in the department. Evan is in the train when Vincent arrives to meet him. Vincent tells him about Muirfield and that signing up with Muirfield is the biggest mistake he made. Evan tells Vincent that it was selfish of him to drag Cat into the middle of all this, so that he could be with her.
Vincent tells Evan that Muirfield will break him down and he will end up giving them Cat’s name. Evan gets pissed and tells him that if Cat decides to be with Vincent, she will end up living her whole life trying to hide from people. At that moment, Evan pushes the panic button and the Muirfield agents appear and tranquilize Vincent. At the precinct, Cat tries to get in touch with Evan, but she cannot get through. JT arrives to meet Cat. Tess joins them. JT tells Cat that Vincent went to meet Evan and he hasn’t heard from him since. He says that he had installed a tracking app on his burner phone, which helped him track Vincent’s movements, but when Vincent reached a particular block at the end of the city, the signal got jammed.
JT and Cat realize that Muirfield got to Vincent. They are worried. Tess takes JT’s tablet and tries to figure out the location. Next, Evan is in Muirfield’s office and he wants to know what is going on. The guy at the desk doesn’t tell him anything. The agent gets up and leaves to go the bathroom. Evan takes advantage of this opportunity and checks the agent’s coat for his access card. He finds it and uses it to go into the records room. He goes through some files and finds Vanessa Chandler’s file. He reads the details and he looks shocked. JT, Tess, and Cat arrive at the facility where Vincent is being kept. They try to figure out ways to get inside. Cat knows that JT has been monitoring Evan’s calls, and she asks him if there were any calls from Claire. He pulls out a call, and Cat says that they can use Claire’s voice as an id to get access.
They blow off the circuit around the fence by dropping an IED into one of the vents. Cat enters the facility and the motion sensors go off. She quickly hides. Evan hears the alarm and quickly walks out of the records room. He accidentally walks into a lab, where he witnesses a gruesome experiment. Some chopped limbs are attached to some machines and they are moving. He is shocked. He sees that Vincent is being kept in a cage and he feels bad for him. The Muirfield agent arrives to meet Vincent and tells him that this is the end for him. At that moment, he receives message about the security breach and he quickly leaves. Evan uses the access card to enter the room and tells Vincent that Muirfield is doing another experiment to create a new kind of cross species.
He tells Vincent that they will cut him open to see what ticks him off. Vincent tells Evan that they already know his trigger, they created him. Evan feels guilty for what he did. He is about to push a button to set Vincent free, when the Muirfield guy arrives and stops Evan. They end up in a fight. The agent shoots Evan. Later, Cat arrives in the room where Vincent is being held and manages to rescue him. She tells Vincent that she needs to get Evan and that she cannot leave him with Muirfield. They find Evan, who is still alive, and try to escape with him. They come across a really strong door and Vincent finds it difficult to break open the door. He tries several times and Evan tells Cat that they need more time.
He tells Cat that he did all this only to protect her. He apologizes for everything. He then sends a text. The Muirfield guys are approaching and Evan walks towards them to stop them. Vincent manages to break open the door. Evan stands in between the approaching Muirfield team and Cat. They shoot Evan. Vincent quickly grabs Cat and escapes. The next day, Cat arrives at the precinct and Gabe tells her that Evan is the mole. He tells her that they received a text from him last night in which he admits that he was acting as cover for the vigilante.
Cat realizes that Evan took the blame. Gabe thinks that Evan skipped town. On their way back, Cat tells Vincent that she has been selfish all this while and that she risked his life. She is upset that Evan also died because of her. Vincent tells her that she risked her life to protect him and that is not being selfish. He tells her that meeting her was the best thing that ever happened to him. He admits that he cannot live without her. The episode ends.